RFE: Add support for bazel based builds in fromager.

[andre-motta]

Many of the packages we currently support at AIPCC require bazel as part of their build process.
Which makes the build process incompatible with fromager's network isolation.

(e.g: torch-xla, jax, jaxlib, runai-model-streamer-gcs, tensorflow)

Bazel builds downloads dependencies while building a package. And there might be very hard to pre-fetch all sources in advance
https://bazel.build/run/build#fetching-external-dependencies
https://bazel.build/run/build#repository-cache

[tiran]

What would you need to build packages with Bazel? An API to run sdist and wheel building without network isolation?

def default_build_wheel(
    ctx: context.WorkContext,
    build_env: build_environment.BuildEnvironment,
    extra_environ: dict[str, str],
    req: Requirement,
    sdist_root_dir: pathlib.Path,
    version: Version,
    build_dir: pathlib.Path,
) -> pathlib.Path:
    return pep517_build_wheel(
        ctx=ctx,
        build_env=build_env,
        extra_environ=extra_environ,
        req=req,
        sdist_root_dir=sdist_root_dir,
        version=version,
        build_dir=build_dir,
        # NEW OPTION
        network_isolation=False,
    )```

[sejohnst]

After a quick search of bazel's documentation, some customization might be feasible. Bazel has an option to use a local cache rather than downloading during the build. Perhaps it's possible to pre-fetch dependencies, build up a local cache, and apply customization to use the local cache.