Fixup script for anonymization

[yarikoptic]

TODOs

• make git-annex invocations optional/autodetected based on presence of .git/annex
• review git-annex behavior -- I think due to dotfiles. we might want some explicit setting to be tuned up in git annex config

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.48%. Comparing base (9e1e601) to head (29d52d8).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #816   +/-   ##
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  Coverage   82.48%   82.48%           
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  Files          42       42           
  Lines        4323     4323           
=======================================
  Hits         3566     3566           
  Misses        757      757           

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[yarikoptic]

@claude review the script modified by this PR - its purpose is to maintain and update mapping for subject ids to new sequentially growing ids. Then

• tune to use git-annex only if it is a git-annex repo (e.g. when there is .git/annex)
• if file starts with period, make script ensure that annex.dotfiles is set to true (git annex config --set annex.dotfiles true )
• add testing (could use e.g. bats or even code in python via pytest etc) that mapping happens as expected and file contains desired mapping