Use bzlmod

[cassiebeckley]

Use the new Bazel module system. This should hopefully help fix the broken re2 import in SPIRV-Tools.

[cassiebeckley]

@dneto0 for review

[dneto0]

Nice, thank you!

[dneto0]

Looks like kokoro/scripts/linux/build-docker.sh needs to request bazel-7.0.2 instead of 5

[cassiebeckley]

@dneto0 I've updated the PR to use the correct Bazel version in Kokoro. I think the kokoro:run label might need to be added again.

[dneto0]

Thanks, and thanks for your patienc.

[dneto0]

Heh. a failure:

INFO: Repository rules_python~0.31.0~python~python_3_11_x86_64-unknown-linux-gnu instantiated at:
  : in 
Repository rule python_repository defined at:
  /root/.cache/bazel/_bazel_root/32ba09432cfff709a688fa7bb9a97efa/external/rules_python~0.31.0/python/repositories.bzl:402:36: in 
ERROR: An error occurred during the fetch of repository 'rules_python~0.31.0~python~python_3_11_x86_64-unknown-linux-gnu':
   Traceback (most recent call last):
	File "/root/.cache/bazel/_bazel_root/32ba09432cfff709a688fa7bb9a97efa/external/rules_python~0.31.0/python/repositories.bzl", line 205, column 25, in _python_repository_impl
		fail("The current user is root, please run as non-root when using the hermetic Python interpreter. See https://github.com/bazelbuild/rules_python/pull/713.")
Error in fail: The current user is root, please run as non-root when using the hermetic Python interpreter. See https://github.com/bazelbuild/rules_python/pull/713.

Looking at that PR, this seems like the useful advice:

bazel-contrib/rules_python#713 (comment)

Which exercises the ignore_root_user_error option introduced in this PR:
https://github.com/bazelbuild/rules_python//commit/e67e7dd719d34d5a13c15b24d0234c1ac753b52d

I started looking at the examples for rules_python. Starting from the docs at https://github.com/bazelbuild/rules_python/blob/main/BZLMOD_SUPPORT.md
and then looking at the first example here:
https://github.com/bazelbuild/rules_python/blob/main/examples/bzlmod/MODULE.bazel#L20
looks like the python.toolchain stanza is what would need the ignore_root_user_error clause.

[dneto0]

Seems like we need:

bazel_dep(name = "rules_python", version = "0.31.0")
python = use_extension("@rules_python//python/extensions:python.bzl", "python")
python.toolchain(
    configure_coverage_tool = False,
    ignore_root_user_error = True,
    python_version = "3.11",
)

I think that's all the necessary pieces?