feature request: "separate-commits" as alternative to "separate-pull-requests" when releasing multiple packages

First off, thanks for maintaining release-please I think it's a great project.

I'm currently frustrated when a PR is created in a monorepo with no root package the commit message will always be `chore: release main` this is bad because there's no transparency as to what packages were released. I'd like to still see a PR with that title, but within it each package release as its own chore commit, then you can not squash them and have complete commits for each release.

If this feature exists already as some feature I couldn't find please point it out!