Add protobuf deserialization to consumer and serialization to producer

[xakep666]

Description

Added protobuf serialization in producer and deserialization in consumer.
To use this user must supply raw .proto schemas by using --proto-file flag and --proto-import-path flag to resolve dependencies mentioned in import sections. User also can supply compiled .protoset file(s) using --protoset-file flag.
Values for flags above also duplicated in config file.

To enable protobuf serialization or deserialization user must specify --value-proto-message flag which contains message type name.

Key may be optionally serialized/deserialized by using flag --key-proto-message.

Fixes #110

Type of change

• New feature (non-breaking change which adds functionality)

Documentation

• the change is mentioned in the ## [Unreleased] section of CHANGELOG.md
• the configuration yaml was changed and the example config in README.md was updated
• a usage example was added to README.md

[d-rk]

Good job @xakep666 👍

I reviewed your PR and the majority of my comments are just cosmetic changes.
The only needed change to the feature itself, would be adding a caching mechanism for retrieving the protobuf descriptors.

[xakep666]

@random-dwi what about linter error (deprecated github.com/golang/protobuf/jsonpb). Is it ok to add exclusion comment or rule for this?

[d-rk]

@xakep666 regarding the linter error, I would prefer not to introduce already deprecated stuff with a PR.
the linter error suggests to replace it by google.golang.org/protobuf/encoding/protojson. Does that require more refactoring then just replacing some parts?

[xakep666]

@xakep666 regarding the linter error, I would prefer not to introduce already deprecated stuff with a PR. the linter error suggests to replace it by google.golang.org/protobuf/encoding/protojson. Does that require more refactoring then just replacing some parts?

@random-dwi This is dependency of protoreflect and there is issue about it jhump/protoreflect#463 so simple replacement is not possible

[d-rk]

@xakep666 I just released version 1.24.0 with the feature included 🎉