Add protoc-gen-openapi (from gnostic)

[fredrikaverpil]

Why this change?

So that we can generate openapiv3 JSON file from protos using protoc-gen-openapi and version control it from Sage.

Notes

Docs: https://github.com/google/gnostic/tree/main/cmd/protoc-gen-openapi

[alethenorio]

Does the package name need to contain the openapi version? The tool seems to be generic so maybe sgprotocgenopenapi is enough?

[fredrikaverpil]

Does the package name need to contain the openapi version? The tool seems to be generic so maybe sgprotocgenopenapi is enough?

@alethenorio good one, I fixed that.

[radhus]

Does the package name need to contain the openapi version? The tool seems to be generic so maybe sgprotocgenopenapi is enough?

Maybe even calling it sggnostic as the tool here is Gnostic and there are other protobuf compilers for OpenAPI 🤓

[fredrikaverpil]

Maybe even calling it sggnostic as the tool here is Gnostic and there are other protobuf compilers for OpenAPI 🤓

The binary is protoc-gen-openapi and you could potentially add another "sgtool" to Sage which downloads and installs a differently named binary from the gnostic project. See here:
https://github.com/google/gnostic/tree/main/cmd/