feat(grpc): multiple proto files

[metalagman]

Reason for This PR

Added support for multiple protobuf files into grpc plugin

Description of Changes

You can now add multiple proto files

# GRPC service configuration
grpc:
    # proto root file
    proto:
        - "proto/test/test.proto"
        - "proto/health/health.proto"

License Acceptance

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

PR Checklist

[Author TODO: Meet these criteria.] [Reviewer TODO: Verify that these criteria are met. Request changes if not]

• [x] All commits in this PR are signed (git commit -s).
• [x] The reason for this PR is clearly provided (issue no. or explanation).
• [x] The description of changes is clear and encompassing.
• [x] Any required documentation changes (code and docs) are included in this PR.
• [x] Any user-facing changes are mentioned in CHANGELOG.md.
• [x] All added/changed functionality is tested.

[rustatian]

The PR isn't ready for review, please, read all comments and the PR checkpoints. You can skip signed commits this time, but next time, please, use at least git commit -s. You need to update the following docs:

• Update roadrunner.dev GRPC documentation.
• Update CHANGELOG.md
• ~Update grpc docs included in the README (grpc/docs/grpc.md).~

[rustatian]

Ok, I'll take care of this PR, since it can be abandoned as PR in the php-grpc with open CR comments. Thanks.