Cleanup up python requirements installation in CI, remove some dangling azure references, refresh python README

[timkpaine]

• removing bespoke package installs/runs in the github actions script (python dependencies and pytest configuration)
  • fixes the very correct complaints in Fix publish issues #1915 (comment) namely, dependencies are derived from a single source of truth that is the setup.py
  • dependencies can still break our CI process, but these should be legitimate breakages of compatibility where a dependency has triggered an incompatibility at run time, rather than some stale hardcoding of a version of dependency in a CI script at ci time
• Remove python readme as it is trivial for it to become stale, instead pull main README during python build/packaging
• Remove azure references from package.json, remove azure build script
• add python 3.10 pypi classifier
• remove .artifactignore azure config file
• add tornado pin < 6.2
• add jupyterlab pin < 4
• add conda installation instructions to python docs
• cleanup some typos and unclear stuff in python docs
• redo of remove separate mock dependency, now part of unittest #1827 now that the docker images are gone (cherry pick from remove separate mock dependency, now part of unittest - fixes #1821 #1925)
• MacOS 10.15 has been long deprecated by GItHub and our CI is failing currently due to brownout.

[timkpaine]

@texodus should trigger a full build so we can verify that grep works on windows 😅

[texodus]

Thanks for the PR! Looks good!

[texodus]

Adding #1924 also