TST: Handle error log with PROJ 8+

[snowman2]

• Identified in PROJ 8 Test Failures #772, related to Default PROJ debug level OSGeo/PROJ#2535
• Tests updated
• Fully documented, including history.rst for all changes and api/*.rst for new API

[codecov]

Codecov Report

Merging #774 (ac93187) into master (31d934f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #774   +/-   ##
=======================================
  Coverage   94.69%   94.69%           
=======================================
  Files          21       21           
  Lines        1528     1528           
=======================================
  Hits         1447     1447           
  Misses         81       81           

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