[Feature] Automatically merge from dev branch to release branch

[makubacki]

Mu changes now go into a dev branch. If the changes are appropriate to go into the corresponding release branch, they are manually cherry-picked. This feature request has the following parts:

1. Add a new checkbox to the PR description that indicates if it should be copied to the release branch
   • Add a label to reflect this as well (e.g. type:include-in-release).
2. Add a dev/* post-merge triggered workflow that will automatically attempt to cherry-pick the merged commits onto the corresponding release/* branch.
   • In case of a conflict, a PR will automatically be created into the release/* branch with the Mu maintainers added as reviewers. Any Mu maintainer can resolve the conflict and update the PR such that it can be merged. Because the conflict resolution may involve new modifications, it will follow the standard two reviewer and status check requirements to be merged into the `release/*' branch.