Add clang-tidy to Github Actions

[GleasonK]

Request description

From feedback in #49 - Add a clang-tidy task to the lint action.

Can be bootstrapped from MHLO:
https://github.com/tensorflow/mlir-hlo/blob/master/.clang-tidy

Additional context

No response

[GleasonK]

Started looking into this, and a few notes:

There are quite a few clang-tidy errors in the files we bootstrapped from mlir-hlo. Because of this I was running clang-tidy-diff to filter by the changes in the git changelist, aka clang-tidy issues that the PR owner is likely responsible for:

git diff -U0 HEAD^ | clang-tidy-diff.py -p1 -path /path/to/stablehlo-build/

Second it seems like clang-tidy takes quite a bit of time to complete (Only being run on StablehloOps.cpp locally on my fairly powerful machine takes 5m37.121s).

Third, maybe someone more familiar with clang-tidy knows better, but it requires a compilation database. Does this mean that it must be run after build and test has completed? We may want to split these action jobs out so that lint doesn't have to occur after build, unless we feel that is right.

This raises the question - how often would we want to run this test? Every PR? If running serially is required, then each update to a PR (even if ccached) may trigger 20+min of actions. I can run these tests in my fork for a bit and get a feel for the overhead.

[GleasonK]

Did some testing last week in actions-tidy branch. The CI environment does not seem to work well with clang-tidy (ref). This trace makes me think it is a configuration issue more than anything. I'll try a few more things like building clang-tidy from llvm source in CI, or installing a different version via package management and running that.

[GleasonK]

Unassigning for now. I hope to get to this in the near future, but this has lower priority than compatibility work, as well as some other early-stage proposals in the works.