[batch-release] A github action for parsing unreleased commit and produce release PR #176425
Description
main doc: flutter.dev/go/batch-release-one-pager
We need a bot to parse unreleased yaml file and produce a release pr.
Steps:
- parse unreleased yaml file from main branch of all opted-in package
- Creates a pr against
releasebranch with the updated changelog, version bump, and unreleased file removed