Tighten security on user info

[imnasnainaec]

Absorbs #3864

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This change is 

[codecov]

Codecov Report

❌ Patch coverage is 44.64286% with 31 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.58%. Comparing base (16bfcc0) to head (5759176).
⚠️ Report is 24 commits behind head on master.

Files with missing lines	Patch %	Lines
Backend/Models/User.cs	0.00%	12 Missing ⚠️
Backend/Controllers/UserController.cs	11.11%	7 Missing and 1 partial ⚠️
Backend/Controllers/ProjectController.cs	0.00%	3 Missing ⚠️
src/components/ProjectUsers/ActiveProjectUsers.tsx	25.00%	3 Missing ⚠️
src/components/ProjectUsers/AddProjectUsers.tsx	0.00%	2 Missing ⚠️
src/components/ProjectUsers/SortOptions.tsx	0.00%	2 Missing ⚠️
src/components/ProjectUsers/UserList.tsx	95.45%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3868      +/-   ##
==========================================
- Coverage   73.72%   73.58%   -0.14%     
==========================================
  Files         287      287              
  Lines       10773    10789      +16     
  Branches     1344     1345       +1     
==========================================
- Hits         7942     7939       -3     
- Misses       2434     2453      +19     
  Partials      397      397              

Flag	Coverage Δ
backend	83.16% <4.16%> (-0.37%)	⬇️
frontend	66.09% <75.00%> (+0.01%)	⬆️

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[andracc]

Reviewed 24 of 25 files at r1, 1 of 1 files at r2, 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @imnasnainaec)