Add pyproject.toml (#28385)

* Add pyproject.toml

Update numpy bounds

* Use subprocess to run grpcio since it is not imported in pyproject.toml

Update setup.py

Remove ImportError from gen_protos.py

Update subprocess run and raise RuntimeError if proto generation fails

Print output of setup.py
Fix linting issues

* Remove build-requirements.txt and use build to build the sdist
Modify buildPython task

* Use wheels to run tox precommit tests

Upgrade pip in Dockerfile

Move _ELEMENTS to shared file. tests are not importable by each other


Add missing element

Remove shared_test_variables

Remove installing wheel in a test suite


Retry run_tox.sh with no installPkg flag

Remove natural language test. codepath is covered in the postCommits.

Add back tox exit code

* Remove cython tests. default tests will run with Cython extensions

FIx toxTask name

Add no-extra test suite to precommit and remove GH duplicate ubuntu test

Skip failing non-cython test

Fix tox test name

* Force type cast inputs to list

* Update stager to use build. If it fails, use legacy setup to build sdist

Fix mypy issue

* Remove cython env and build-requirements for tox.ini