Bazelify go-protoparser, and use it in CI tests

[shaldengeki]

This is a quick first pass at using Bazel in go-protoparser. This makes the CI tests run via Bazel. You can do the same on your machine, by running bazel test //.... If you don't have bazel, recommend you install bazelisk, which will manage your bazel version for you:
https://bazel.build/install/bazelisk

Roughly, this is the result of:

• Setting up a WORKSPACE and root BUILD.bazel file, with go rules and gazelle in it
• Running gazelle against the repo: bazel run //:gazelle, to generate BUILD.bazel files for every package
• Changing _example/dump/main.go to read _testdata/simple.proto as a default argument at runtime
• Changing the Makefile to run bazel commands where possible
• Updating the Github workflow to use a persistent Bazel cache
• Adding some Bazel configuration to display useful test failures

You can see the benefits of the caching in CI, if you rerun the builds -- you'll see that Bazel correctly doesn't re-run the tests again, and the build finishes very quickly:
https://github.com/shaldengeki/go-protoparser/actions/runs/7945280017/job/21691752664

INFO: Elapsed time: 6.377s, Critical Path: 0.09s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action
//interpret/unordered:unordered_test                            (cached) PASSED in 0.1s
//lexer:lexer_test                                              (cached) PASSED in 0.1s
//lexer/scanner:scanner_test                                    (cached) PASSED in 0.1s
//parser:parser_test                                            (cached) PASSED in 0.1s
//parser/meta:meta_test                                         (cached) PASSED in 0.1s
Executed 0 out of 5 tests: 5 tests pass.

(Or you can run bazel test //... locally twice, and observe that the second run finishes ~instantly.)

I left the linting commands & job un-Bazelified. I think this'll take some more work -- basically, some of the linting packages take some work to bazelify, and doing it only partway will make the lint CI job slow (~40s).

Let me know what you think! I'm happy to keep plugging away at the lints if you'd rather do this in one fell swoop.

[yoheimuta]

Thank you for your fantastic work!

I have a question. Is there anything new contributors need to know before diving into this repository? Do they just need to install bazelisk? I assume some developers might not be familiar with bazel, so I'd like to add some instructions on setup and any changes to the standard Go workflow.

[ehrktia]

@shaldengeki
out of curiosity, I have the following queries

• from my understanding bazel build system is used mostly in mono repos with polygot code, i.e. - repo with front and back ends together to optimise build and CI run time.
  This is go go-based repo/lib can it not use the standard go build system go run, go build and go test both in CI and in local env to achieve the same?
• As per the comment about caching test in local and build can we not use the go test flags to achieve the same?
  Am new to Bazel i.e. - have used it commercially for a year or so not more.
  The above queries are based on my understanding of Bazel.