docs: fix and update docstrings

[sanzoghenzo]

As discussed with @jmcouffin on the forum, this PR updates and fixes some of the docstrings of the pyrevit package.

There are still many functions and methods without docstrings, and some docstring without the arguments and types description, but it's a start to have better documented code.

Some of the style choices (for example the return types between parenthesis) were a consequence of my desire to move to the more modern, markdown-centric, MkDocs documentation builder instead of sphinx, and some shortcomings found in mkdocstrings plugin, already discussed in the forum.

I added ruff to the root python 3.10 toolchain and enabled the documentation ("D") checks because of the vast performance gain over pylint; it could be used also for other checks and maybe for git pre-commit hooks and CI jobs in order to allow only clean code to be committed (but this is another story...).