docs: drop sphinx and use doxygen exclusively

[ReenigneArcher]

Description

This PR drops sphinx/python docs and will use doxygen exclusively.

Todo:

• [x] Get build working on readthedocs, preview: https://lizardbyte--2932.org.readthedocs.build/projects/sunshine/en/2932/
• [x] Get all other builds working
• [x] Convert remaining rst files to markdown
• [x] adjust admonitions... hopefully we can just use GitHub style... see: https://github.com/jothepro/doxygen-awesome-css/issues/152 ... maybe some other options https://bobbyhadz.com/blog/github-markdown-alert-admonition-box
• [ ] fix code blocks that contain doxygen comment examples, maybe move to .github repo?... see: https://github.com/jothepro/doxygen-awesome-css/issues/154

see: https://github.com/LizardByte/libdisplaydevice/pull/71

Screenshot

Issues Fixed or Closed

Type of Change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Dependency update (updates to dependencies)
• [x] Documentation update (changes to documentation)
• [x] Repository update (changes to repository files, e.g. .github/...)

Checklist

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have added or updated the in code docstring/documentation-blocks for new or existing methods/components

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 9.65%. Comparing base (adf068e) to head (abcfe32). Report is 138 commits behind head on master.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #2932   +/-   ##
======================================
  Coverage    9.65%   9.65%           
======================================
  Files          97      97           
  Lines       17557   17557           
  Branches     8230    8230           
======================================
  Hits         1696    1696           
  Misses      12998   12998           
  Partials     2863    2863           

Flag	Coverage Δ
Linux	7.16% <ø> (ø)
Windows	5.08% <ø> (ø)
macOS-12	10.29% <ø> (ø)
macOS-13	10.21% <ø> (+0.01%)	:arrow_up:
macOS-14	10.52% <ø> (ø)

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[ReenigneArcher]

@cgutman FYI