CI: Expand/improve test coverage

[samuel-jimenez]

Consolidate testing, coverage jobs. test jobs now upload coverage results unless disabled with matrix.no_coverage option.
Update ubuntu-20.04 runners to ubuntu-22.04 for actions/runner-images#11101.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.57%. Comparing base (0cc0c62) to head (e4fc5d5).
Report is 162 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2357       +/-   ##
===========================================
+ Coverage   30.91%   70.57%   +39.66%     
===========================================
  Files          53       65       +12     
  Lines       20112    36293    +16181     
  Branches     9755        0     -9755     
===========================================
+ Hits         6217    25613    +19396     
- Misses       7922    10680     +2758     
+ Partials     5973        0     -5973     

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