Add Implementation for otlp udp exporter

[jj22ee]

Description:

Implementing a Golang UDP exporter for OTLP spans for an AWS Lambda environment.

• OTel spans is first protobuf encoded, then base64 encoded, then prefixed with T1S (Sampled Spans Prefix), and finally appended to the '{"format":"json","version":1}\n' string before being exported to the address provided to the UDP Exporter or default 127.0.0.1:2000.
• UDP Exporter class name otlptraceudp follows OTel Go exporters like otlptracegrpc and otlptracehttp
• If in an AWS Lambda Environment, use AWS_XRAY_DAEMON_ADDRESS env var as the default address instead of 127.0.0.1:2000.

Link to tracking Issue:

Testing:

cd ./exporters/otlptraceudp
go test ./...

Tested with OTel Sample App for Lambda Go: https://github.com/open-telemetry/opentelemetry-lambda/blob/main/go/sample-apps/function/function.go
Updated TracerProvider to be like:

	daemonAddress := os.Getenv("AWS_XRAY_DAEMON_ADDRESS")
	myudpexporter, _ := otlptraceudp.New(ctx, otlptraceudp.WithEndpoint(daemonAddress))

	tp := trace.NewTracerProvider(trace.WithSpanProcessor(trace.NewSimpleSpanProcessor(myudpexporter)))

Raw span from Lambda

{
    "Id": "1-67c0d852-210aa54e1b267ff37ce7f51b",
    "Duration": 0.125,
    "LimitExceeded": false,
    "Segments": [
        {
            "Id": "0289ef4deea9b744",
            "Document": {
                "id": "0289ef4deea9b744",
                "name": "go-udp-testing",
                "start_time": 1740691538.571,
                "trace_id": "1-67c0d852-210aa54e1b267ff37ce7f51b",
                "end_time": 1740691538.696,
                "http": {
                    "response": {
                        "status": 200
                    }
                },
                "aws": {
                    "request_id": "9e463e5f-eb23-43a3-b3bb-61c63fe55225"
                },
                "origin": "AWS::Lambda",
                "resource_arn": "arn:aws:lambda:us-east-1:123456789012:function:go-udp-testing"
            }
        },
        {
            "Id": "36b27711568a12dc",
            "Document": {
                "id": "36b27711568a12dc",
                "name": "go-udp-testing",
                "start_time": 1740691538.576232,
                "trace_id": "1-67c0d852-210aa54e1b267ff37ce7f51b",
                "end_time": 1740691538.6961966,
                "parent_id": "0289ef4deea9b744",
                "aws": {
                    "account_id": "123456789012",
                    "function_arn": "arn:aws:lambda:us-east-1:123456789012:function:go-udp-testing",
                    "cloudwatch_logs": [
                        {
                            "log_group": "/aws/lambda/go-udp-testing"
                        }
                    ],
                    "resource_names": [
                        "go-udp-testing"
                    ]
                },
                "origin": "AWS::Lambda::Function",
                "subsegments": [
                    {
                        "id": "0716f80c05e26051",
                        "name": "Invocation",
                        "start_time": 1740691538.576332,
                        "end_time": 1740691538.6958847,
                        "aws": {
                            "function_arn": "arn:aws:lambda:us-east-1:123456789012:function:go-udp-testing"
                        }
                    },
                    {
                        "id": "a2e43621571698fb",
                        "name": "Overhead",
                        "start_time": 1740691538.6959248,
                        "end_time": 1740691538.6961403,
                        "aws": {
                            "function_arn": "arn:aws:lambda:us-east-1:123456789012:function:go-udp-testing"
                        }
                    }
                ]
            }
        },
        {
            "Id": "b113328b83442634",
            "Document": {
                "id": "b113328b83442634",
                "name": "unknown_service:bootstrap",
                "start_time": 1740691538.576584,
                "trace_id": "1-67c0d852-210aa54e1b267ff37ce7f51b",
                "end_time": 1740691538.6255057,
                "parent_id": "0716f80c05e26051",
                "aws": {
                    "lambda.invoked_arn": "arn:aws:lambda:us-east-1:123456789012:function:go-udp-testing"
                },
                "annotations": {
                    "span.name": "go-udp-testing",
                    "span.kind": "SERVER"
                },
                "metadata": {
                    "telemetry.sdk.language": "go",
                    "faas.invocation_id": "9e463e5f-eb23-43a3-b3bb-61c63fe55225",
                    "service.name": "unknown_service:bootstrap",
                    "cloud.account.id": "123456789012",
                    "telemetry.sdk.version": "1.34.0",
                    "telemetry.sdk.name": "opentelemetry"
                },
                "subsegments": [
                    {
                        "id": "d87989e76f7c69cc",
                        "name": "HTTP GET",
                        "start_time": 1740691538.6223142,
                        "end_time": 1740691538.6250916,
                        "http": {
                            "request": {
                                "url": "https://api.github.com/repos/open-telemetry/opentelemetry-go/releases/latest",
                                "method": "GET"
                            },
                            "response": {
                                "status": 200
                            }
                        },
                        "annotations": {
                            "span.name": "HTTP GET",
                            "span.kind": "CLIENT"
                        },
                        "metadata": {
                            "net.peer.name": "api.github.com",
                            "http.status_code": 200,
                            "telemetry.sdk.language": "go",
                            "service.name": "unknown_service:bootstrap",
                            "http.url": "https://api.github.com/repos/open-telemetry/opentelemetry-go/releases/latest",
                            "telemetry.sdk.version": "1.34.0",
                            "http.method": "GET",
                            "telemetry.sdk.name": "opentelemetry"
                        },
                        "namespace": "remote"
                    },
                    {
                        "id": "c82ce0147e264b58",
                        "name": "S3",
                        "start_time": 1740691538.5766907,
                        "end_time": 1740691538.6221228,
                        "http": {
                            "response": {
                                "status": 200
                            }
                        },
                        "aws": {
                            "region": "us-east-1",
                            "request_id": "ZYPJZ1QBG7NDBYN2"
                        },
                        "annotations": {
                            "span.name": "S3.ListBuckets",
                            "span.kind": "CLIENT"
                        },
                        "metadata": {
                            "http.status_code": 200,
                            "telemetry.sdk.language": "go",
                            "service.name": "unknown_service:bootstrap",
                            "rpc.service": "S3",
                            "rpc.method": "ListBuckets",
                            "telemetry.sdk.version": "1.34.0",
                            "rpc.system": "aws-api",
                            "telemetry.sdk.name": "opentelemetry"
                        },
                        "namespace": "aws"
                    }
                ]
            }
        },
        {
            "Id": "010fdb49177e6f32",
            "Document": {
                "id": "010fdb49177e6f32",
                "name": "HTTP GET",
                "start_time": 1740691538.6223142,
                "trace_id": "1-67c0d852-210aa54e1b267ff37ce7f51b",
                "end_time": 1740691538.6250916,
                "parent_id": "d87989e76f7c69cc",
                "inferred": true,
                "http": {
                    "request": {
                        "url": "https://api.github.com/repos/open-telemetry/opentelemetry-go/releases/latest",
                        "method": "GET"
                    },
                    "response": {
                        "status": 200
                    }
                }
            }
        },
        {
            "Id": "1c6e82bf212279b5",
            "Document": {
                "id": "1c6e82bf212279b5",
                "name": "S3",
                "start_time": 1740691538.5766907,
                "trace_id": "1-67c0d852-210aa54e1b267ff37ce7f51b",
                "end_time": 1740691538.6221228,
                "parent_id": "c82ce0147e264b58",
                "inferred": true,
                "http": {
                    "response": {
                        "status": 200
                    }
                },
                "aws": {
                    "region": "us-east-1",
                    "request_id": "ZYPJZ1QBG7NDBYN2"
                },
                "origin": "AWS::S3"
            }
        }
    ]
}

Documentation:

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[lukeina2z]

Looks great. Please measure the test coverage before the merge 'go test -cover ./...'