fix: Make review settings history usable (fixes #3213).

[kivinen]

Makes the history of the review settings usable, by filtering out useless "skipped" and "None" entries from the list unless they have some actual changes to the settings (i.e., if the delta change count is not zero). Also do not save settings every single time when document is assigned to anybody for everybody, i.e., only do bulk update for those users whose skip_next count was decremented. Added some more useful change reasons.

This should fix #3213.

[codecov]

Codecov Report

Attention: Patch coverage is 69.69697% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 88.92%. Comparing base (187c2c5) to head (9239dc3).
Report is 62 commits behind head on main.

Files	Patch %	Lines
ietf/doc/templatetags/ietf_filters.py	28.57%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7205      +/-   ##
==========================================
- Coverage   88.98%   88.92%   -0.07%     
==========================================
  Files         291      291              
  Lines       40717    41090     +373     
==========================================
+ Hits        36233    36540     +307     
- Misses       4484     4550      +66     

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