New SharedDomain extension

[jyeshe]

Validation Steps

i) Register a new user ii) Create a new user via super user UI ii) Create a new project via super user UI

Notes for the reviewer

Allows adding other entities while registering a new user or creating a new project. It's called whenever a new user is registered and a new project is created.

Related issue

Fixes #2029

Review checklist

• [x] I have performed a self-review of my code
• [x] I have verified that all appropriate authorization policies (:owner, :admin, :editor, :viewer) have been implemented and tested
• [x] If needed, I have updated the changelog
• [ ] Product has QA'd this feature

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 90.07%. Comparing base (50e2efd) to head (117fd3e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2025      +/-   ##
==========================================
+ Coverage   90.04%   90.07%   +0.02%     
==========================================
  Files         249      251       +2     
  Lines        8219     8228       +9     
==========================================
+ Hits         7401     7411      +10     
+ Misses        818      817       -1     

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