Update sphinx to use new sphinx.ext.apidoc extension

[djhoese]

Updates sphinx to 8.2 which adds a sphinx.ext.apidoc extension and replaces sphinxcontrib.apidoc. I also turned off documenting most test modules which cuts off ~30 seconds (50%) of execution time and ~2GB of memory usage (80%).

• Closes #xxxx
• Tests added
• Fully documented
• Add your name to AUTHORS.md if not there already

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.11%. Comparing base (17cf0ce) to head (9b43c72).
Report is 472 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3068      +/-   ##
==========================================
- Coverage   96.14%   96.11%   -0.04%     
==========================================
  Files         383      383              
  Lines       55785    55685     -100     
==========================================
- Hits        53636    53523     -113     
- Misses       2149     2162      +13     

Flag	Coverage Δ
behaviourtests	3.88% <ø> (+<0.01%)	⬆️
unittests	96.21% <ø> (-0.04%)	⬇️

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[djhoese]

I'm not pleased with one thing I see so far in the docs. The "Satpy API" link on the home page says "satpy package". I think Sphinx is getting confused because for some reason the new api/modules.rst file doesn't have a title and it is ignoring our forced title in index.rst.

[djhoese]

When sphinx-doc/sphinx#13391 is merged and released it will fix the API title issue I mentioned in my previous comment.

[mraspaud]

Thanks for sorting this out! I’m totally fine with not building documentation for the tests.
LGTM.