Add module for converting docstrings to numpydoc format

[taldcroft]

Description

This provides a module (and eventually a command line script) to convert from ReST format docstrings to numpydocs format.

I spent some time trying to use the pyment package but found that it does not handle any docstring with inline examples. After an hour trying to make that package work I bailed. In the end some customization was useful -- we have used non-standard conventions in docstrings over the years and this code tries to do the best with what's there.

The ReST format which is used in most Ska packages is unsatisfactory because it does not really support indicating the type of input parameters. It is also a bit tired and doesn't look nice.

Interface impacts

None

Testing

Unit tests

• No unit tests

Functional tests

See sot/chandra_aca#156 and rendered output in the description.

[taldcroft]

@javierggt - this includes some unrelated changes which fix ruff warnings. These are obvious in the diffs. Let me know if these are not OK.