refactor: upgrade protoc-gen-grpc-gateway to use the new Go code generator

[adambabik]

References to other Issues or PRs

This is initial work to refactor how the gRPC Gateway files are generated in order to fix a problem described in #1612.

Brief description of what is fixed or changed

This change upgrades protoc-gen-grpc-gateway to use google.golang.org/protobuf/compiler/protogen which is the new package for writing protoc plugins generating Go code.

It also fixes all places to use packages from google.golang.org/protobuf module instead of github.com/golang/protobuf.

Other comments

I tested it by running go test ./... and regenerating all examples/internal/proto/examplepb/*.gw.go files using protoc with a new bin/protoc-gen-grpc-gateway binary. There were no changes.

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[adambabik]

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[adambabik]

It seems like I need to update Bazel BUILD files. Is there a way to regenerate them or I should fix them manually?

[achew22]

@adambabik thanks for your contribution! I'm extremely excited for this one. Assuming the major structure hasn't changed (looking through the PR it doesn't look like it but I won't rule it out entirely), you should be able to invoke http://godoc.org/github.com/bazelbuild/bazel-gazelle/cmd/gazelle in the root of the repo and it will generate all the BUILD file changes for you. If that doesn't work, please post back here and I'll fix them manually on your PR

[johanbrandhorst]

This is a really impressive piece of work. I haven't looked at it yet but I think you'll find that we can't replace the old github.com/golang/protobuf imports yet because of how bazel imports them. If you revert the import changes (for now) it should be possible to regenerate the files using the commands listed in CONTRIBUTING.md.

[adambabik]

@achew22 thanks, it seems that it worked and the CI pipeline is happy :)

@johanbrandhorst Thanks! It's just a first step actually, there will be more changes to fully embrace protogen.Plugin. Here, I merely wrapped the existing code into it.

I actually managed to run the commands from CONTRIBUTING.md regenerating files with the existing changes and they did not complain. Do you think I still should revert to github.com/golang/protobuf imports due to some reason?

[johanbrandhorst]

This looks great, thank you so much for taking the time to get this done! I understand it's just the start, but great work!

[johanbrandhorst]

Thanks for your contribution!

[achew22]

To echo Johan even more, thank you so much! I think this will really help cut down on the bugs we get where there is some weird flag parsing thing that I implement incorrectly 5 years ago 😁

[adambabik]

Thank you folks! :) I will continue working on the next PR to fully embrace protogen package.