RFR: 1199: Enforce maintainer approval in JBS before allowing to integrate backports into updates projects

[Zhao Song]

As Erik said in the description of this issue, currently, this issue only cares about tracking approval labels in the related bugs.

If a repository is set up with the "approval" configuration, pull requests in that repository will require the maintainer's approval in JBS. Otherwise, the pull request will not be considered ready. 

Erik has also provided a design outlining how to configure the "approval" for a repository.


The simple case, where the labels are the same for every branch in a repository: 

"approval": { 
  "request": "jdk17u-fix-request", 
  "approved": "jdk17u-fix-yes", 
  "rejected": "jdk17u-fix-no", 
} 

To reduce the need for changing multiple strings when copying a configuration for a new repository, there is an optional "prefix" field: 

"approval": { 
  "prefix": "jdk17u-fix-", 
  "request": "request", 
  "approved": "yes", 
  "rejected": "no", 
} 

When there are multiple branches with different labels, having the prefix set per branch can help reduce the size of the configuration significantly: 

"approval": { 
  "request": "-critical-request", 
  "approved": "-critical-approved", 
  "rejected": "-critical-rejected", 
  "branches": [ 
    "jdk20\.0\.1": { "prefix": "CPU23_04" } 
  ] 
}

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Commit messages:
 - SKARA-1199

Changes: https://git.openjdk.org/skara/pull/1537/files
 Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1537&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-1199
  Stats: 265 lines in 9 files changed: 244 ins; 2 del; 19 mod
  Patch: https://git.openjdk.org/skara/pull/1537.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1537/head:pull/1537

PR: https://git.openjdk.org/skara/pull/1537