refactor: re-organize PR linter

[rix0rrr]

The PR linter code was a bit of a mess; evaluating rules and mutating the PR was interspersed, generic GitHub code was mixed with CDK-specific code, the linter could be triggered from multiple sources, none of them were documented very well.

Try to rectify all of that in this PR to make it easier to extend the PR linter in the future:

• Split the linter into clear evaluate/act responsibilities.
• Split code across more than 1 file.
• Document how the "PR Linter Trigger" works
• Streamline how we get a PR number into the linter.
• Give an example of how to run it locally to test the rule evaluation on real PRs

Not every crazy design decision has been rectified yet, but at least we have a start of something a little more comprehensible. Another change I made: the old PR linter creates a comment + a review with the same content (but not quite). In this PR, make it just do reviews and don't do comments.

This started from a PR that had CodeCov changes added, but I want to do a refactor without feature changes first before adding new code.

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.48%. Comparing base (74bd8ce) to head (935a77b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #32969   +/-   ##
=======================================
  Coverage   81.48%   81.48%           
=======================================
  Files         226      226           
  Lines       13768    13768           
  Branches     2416     2416           
=======================================
  Hits        11219    11219           
  Misses       2271     2271           
  Partials      278      278           

Flag	Coverage Δ
suite.unit	81.48% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
packages/aws-cdk	80.89% <ø> (ø)
packages/aws-cdk-lib/core	82.10% <ø> (ø)

[iliapolo]

Was this always the logic? only fail the linter if it requests changes?

[rix0rrr]

Yes.

[mrgrain]

I trust you to fix problems

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 935a77b
• Result: SUCCEEDED
• Build Logs (available for 30 days)

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[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[github-actions]

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