[bazel] add python targets (#101003)
This PR adds bazel python, so that bazel build could be used from python like `import torch`.
Notable changes:
- Add the python targets.
- Add the version.py.tpl generation.
- In order to archive the `USE_GLOBAL_DEPS = False` just for the bazel build, employ a monkey-patch hack in the mentioned `version.py.tpl`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/101003
Approved by: https://github.com/huydhn
