Add network to configfile for Docker runners

[czoido]

Changelog: Feature: Add network to configfile for Docker runners.
Docs: TODO

This lets you add the network to the docker run, this was very useful for me while trying to debug this #16834 launching a local docker artifactory.

Leaving in draft because we can't test this...

image: my-conan-runner-image
build:
    dockerfile: /Users/barbarian/runner/mylib
    build_context:  /Users/barbarian/runner/mylib
    build_args:
        BASE_IMAGE: ubuntu:22.04
run:
    name: my-conan-runner
    containerEnv:
        CONAN_PASSWORD_SERVER: password
        CONAN_LOGIN_USERNAME_SERVER: admin
    network: my-network