[META] Allow to bump generic version references via new bumpVersions config option

[secustor]

This will exists for the foreseeable future side by side with bumpVersion which allows managers to define version locations to be bumped.

discussion: #27602

{
  "bumpVersions": [{
     "fileMatch": "< a file pattern >",
     "semverLevel": "<major|minor|patch>",
     "matchStrings": [
       "<a regex with a 'version' capture group"
     ]
  },{
     "fileMatch": "README.md",
     "semverLevel": "minor",
     "matchStrings": [
       "version:\\s+(?<version>\\S*)"
     ]
  }]
}

• allow managers to bump multiple files
• add bumpVersions field as experimental