[Proposal] Enhancing AssignREplicas with Plugins

[Vacant2333]

What type of PR is this?
/kind feature

Which issue(s) this PR fixes:
From: #4919

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 28.53%. Comparing base (a87ec2a) to head (fd852bf).
Report is 121 commits behind head on master.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5218      +/-   ##
==========================================
+ Coverage   28.23%   28.53%   +0.30%     
==========================================
  Files         632      632              
  Lines       43723    43856     +133     
==========================================
+ Hits        12345    12515     +170     
+ Misses      30473    30443      -30     
+ Partials      905      898       -7     

Flag	Coverage Δ
unittests	28.53% <ø> (+0.30%)	⬆️

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