Switch to bzlmod by default.
* Prebuilt wheel testing (`--//jax:build_jax=false` and `--//jax:build_jaxlib=false`):
- Under Bzlmod, pip packages are exposed through `@pypi//<package>` rather than standalone `@pypi_<package>` repositories. This change updates `//:jax_wheel_with_internal_test_util` in `BUILD.bazel` to reference `@pypi//jax:whl`.
- Because `pip.parse` only generates repository targets for packages listed in the lockfile, `jax` is now included in `build/requirements.in` and the lockfiles.
- Adding `jax` and `jaxlib` to `local_wheels` in `MODULE.bazel` allows `.whl` files in `dist/` to override PyPI dependencies when running tests against prebuilt wheels.
- The `rules_python_local_wheel` patch now formats local wheel URIs with `file:///` and prevents `urllib.bzl` from stripping leading slashes from file schemes. This fixes `UnknownHostException: usr` download errors when Bazel fetches local wheels.
* ROCm and SYCL C++ toolchains (`MODULE.bazel`):
- Registering the ROCm and SYCL hermetic C++ toolchains in `MODULE.bazel` ensures ROCm builds use Clang instead of host gcc, which fixes build failures caused by `-Qunused-arguments`.
* Nobuild CI check (`build/BUILD.bazel`):
- Exporting `REQUIREMENTS_TXT` in `build/BUILD.bazel` resolves missing `//:requirements.txt` errors during `--nobuild` analysis checks under Bzlmod.
