This PR is required in order to upgrade to the `master` branch version of protobuf. To do this, we upgrade to the latest version of `rules_python` by:
- Adding in explicit dependencies on all PyPi Bazel test dependencies
- Resolving the circular dependency this creates for `xds-protos` by giving it a Bazel build
- Generating the Python code for `xds-protos` as part of `generate-projects.sh` since doing so directly in Bazel would be highly fragily, dependent on many other projects' Bazel builds
Closes#34945
PiperOrigin-RevId: 599875020
* New Python package xds_protos
* Polish the setup.py
* Adding install requirements and improve wheel validation
* Add xds-protos to the update procedure of envoy-api
* Add setup requirements