Add support for local wheel files in hermetic python
Add support for local wheel files in hermetic python

This allows users to specify a list of workspaces that contain pre-built local wheels without need to manually add them in requirements.txt files. 

The wheels will be automatically processed by bazel rules and injected into the requirements_lock_<py_version>.txt on the fly (assuming `HERMETIC_PYTHON_VERSION=py_version`).

This feature is mainly inspired by pytorch/xla demand, since building pytorch/xla implies first building pytorch repo locally and then pointing to its artifacts (both raw .so files and entire .whl) in pytorch/xla build.

This also helps JAX to facilitate build_jaxlib=false case, as it would eliminate need to manually update requirements_locak.txt files in JAX CI as well.
