extract: --skip-errors ignores corrupted chunks (w/ log message), see #840

[ThomasWaldmann]

Forward port of a change implemented by @enkore back in 2016:

https://github.com/enkore/borg/commit/09b21b117c6d34032a9483dd82086a4fae532cb6

[codecov-commenter]

Codecov Report

Merging #7481 (ec1937d) into master (1f48e50) will decrease coverage by 0.43%. The diff coverage is 89.47%.

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@@            Coverage Diff             @@
##           master    #7481      +/-   ##
==========================================
- Coverage   83.69%   83.27%   -0.43%     
==========================================
  Files          66       66              
  Lines       11853    11877      +24     
  Branches     2149     2144       -5     
==========================================
- Hits         9920     9890      -30     
- Misses       1359     1400      +41     
- Partials      574      587      +13     

Files	Coverage Δ
src/borg/archiver/extract_cmd.py	92.00% <100.00%> (+0.24%)	:arrow_up:
src/borg/archive.py	83.52% <88.23%> (-0.77%)	:arrow_down:

... and 10 files with indirect coverage changes