Generate inheritance diagrams for models and submodels in the documentation

[agriyakhetarpal]

Description

Adds a Sphinx autodoc extension that appends inheritance diagrams for models and submodels classes in their docstrings, using a dropdown from sphinx-design, and sphinx.ext.inheritance_diagram – which uses graphviz to generate a unidirectional graph in .SVG format that displays derived classes for a particular class.

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ pre-commit run (see CONTRIBUTING.md for how to set this up to run automatically when committing locally, in just two lines of code)
• All tests pass: $ python run-tests.py --all
• The documentation builds: $ python run-tests.py --doctest

You can run unit and doctests together at once, using $ python run-tests.py --quick.

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.01 ⚠️

Comparison is base (c494873) 99.71% compared to head (109adce) 99.71%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3074      +/-   ##
===========================================
- Coverage    99.71%   99.71%   -0.01%     
===========================================
  Files          248      248              
  Lines        18749    18747       -2     
===========================================
- Hits         18695    18693       -2     
  Misses          54       54              

Impacted Files	Coverage Δ
pybamm/input/parameters/lithium_ion/Prada2013.py	100.00% <100.00%> (ø)

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[agriyakhetarpal]

The built docs can be checked here: https://pybamm--3074.org.readthedocs.build/en/3074/

[valentinsulzer]

thanks, looks good