Switched to snooty package for Python.

[lextm]

Made a few changes to simplify the language server acquisition,

1. Users of this extension should have Python installed (due to reStructuredText usage), so shipping a Python package snooty is easier than shipping zipped binaries.
2. Created a Python package on PyPI, https://pypi.org/project/snooty/
3. Revised the extension to detect snooty package for Python and install it if not present.
4. Deleted all unused code.

If your team want to take ownership of the Python package, let me know who I should add as owner there.

I also revised reStructuredText extension for VSCode to use snooty as language server. Hope to collaborate in the future with your team to improve the language server experience.

[lextm]

Found it is not quite obvious to me how to use snooty.languageServerPath to debug locally, so I implemented a debugpy based approach to enable language server debugging.