FR: Enable git flow patterns

[codytipton-hpg]

Currently release-please-action appears to be limited mostly to a github flow branching strategy.

E.g. if I wanted to cut release branches from develop, and merge them into master, I could set my default_branch to master, but trigger release-please-action on push to develop. The problem with this is that CHANGELOG.md or other updates added to the release-v*.. branch by release-please would be absent from develop, and subsequent Release PR merge conflicts would arise.

I'm not sure how to work around this short of an option to disable automated changelog and other commits... Perhaps an option to add the changelog (or other release-type specific) commits to the initial PR into develop based on the existing fix/feat commit messages when a label is included (e.g. label: release-me)-> generate release PR on merge to develop, with a merge target of main.

[ChipWolf]

Also interested in this, we'd like a feature branch -> dev -> prod git flow with prereleases on develop We've achieved prereleases on dev and releases on prod with some hacking, but it'd be ideal to automate the dev -> prod promotion with the same release PR.