Autogenerate api docs

[je-cook]

Description

Closes #3834
Closes #1532
possibly also #2936

This

• Adds auto api docs generation
• removes most of the vardes stuff
• converts all the docstrings to use the numpy docstring style because autoformatting of sphinx api docs is on the whole no supported by mkdocs (many features are missing).

Most of the docs changes were done automatically by the pyment package with some manual fixes afterwards.

This adds a few docs dependencies too.

Sorry its so long...

Checklist

I confirm that I have completed the following checks:

• My changes follow the PROCESS style guide
• I have justified any large differences in the regression tests caused by this pull request in the comments.
• I have added new tests where appropriate for the changes I have made.
• If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
• If I have made documentation changes, I have checked they render correctly.
• I have added documentation for my change, if appropriate.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 96.10390% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.73%. Comparing base (9b6c78a) to head (f33e6e3).

Files with missing lines	Patch %	Lines
process/io/costs_bar.py	0.00%	1 Missing ⚠️
process/io/data_structure_dicts.py	50.00%	1 Missing ⚠️
process/io/process_config.py	94.11%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4097      +/-   ##
==========================================
+ Coverage   46.57%   46.73%   +0.16%     
==========================================
  Files         124      124              
  Lines       29042    29132      +90     
==========================================
+ Hits        13526    13615      +89     
- Misses      15516    15517       +1     

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[timothy-nunn]

Couple of concerns before I continue reviewing. The auto converter seems to be not getting the formatting quite correct