Provisional RateLimitPolicy proposal

[bjee19]

Proposed changes

Problem: Users want to configure Rate Limiting in NGINX.

Solution: Create the provisional RateLimitPolicy enhancement proposal.

Partially implements: #4059

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.10%. Comparing base (24547c6) to head (dcf9f34).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4324   +/-   ##
=======================================
  Coverage   86.09%   86.10%           
=======================================
  Files         132      132           
  Lines       14342    14342           
  Branches       35       35           
=======================================
+ Hits        12348    12349    +1     
+ Misses       1791     1790    -1     
  Partials      203      203           

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