Implement workflow run approval

[gsmet]

Description

This pull request implements workflow run approval.

@bitwiseman my dear colleague @holly-cummins needs it for some Quarkus related work so if you have plans to release something soon, we would appreciate if this could get in.
Thanks!

[codecov]

Codecov Report

Merging #1504 (de1345b) into main (e5fb0cd) will increase coverage by 0.09%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##               main    #1504      +/-   ##
============================================
+ Coverage     78.88%   78.97%   +0.09%     
- Complexity     2124     2128       +4     
============================================
  Files           204      204              
  Lines          6456     6460       +4     
  Branches        361      361              
============================================
+ Hits           5093     5102       +9     
+ Misses         1153     1148       -5     
  Partials        210      210              

Impacted Files	Coverage Δ
...rc/main/java/org/kohsuke/github/GHWorkflowRun.java	89.70% <100.00%> (+1.82%)	⬆️
.../org/kohsuke/github/GHWorkflowRunQueryBuilder.java	66.66% <100.00%> (+4.16%)	⬆️
.../org/kohsuke/github/GHPullRequestQueryBuilder.java	95.00% <0.00%> (+20.00%)	⬆️

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