Adds user permissions when updating group permissions to projects without the user

[hkethi002]

Review Checklist

• Tests were added to cover all code changes
• Documentation was added / updated
• Code and tests follow standards in CONTRIBUTING.md

[codecov-io]

Codecov Report

Merging #933 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #933      +/-   ##
=========================================
+ Coverage   90.19%   90.2%   +<.01%     
=========================================
  Files          48      48              
  Lines        6418    6419       +1     
=========================================
+ Hits         5789    5790       +1     
  Misses        629     629

Flag	Coverage Δ
#python	90.2% <100%> (ø)	⬆️

Impacted Files	Coverage Δ
api/handlers/listhandler.py	90.67% <100%> (+0.02%)	⬆️

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[nagem]

It's too bad it'll take two calls, but changes look good. Maybe we can redesign how we propagate permissions at some point to make it a little smoother.