Extend Release Tools to support the new changelog setup in parallel with the old one
When the changelog generation API is in place, we need to extend Release Tools so it supports both the old and new approach in parallel. Release Tools will default to the old approach, but when a project specific feature flag is set, the new setup is used for that project. For example, setting the Release Tools feature flag gitaly_new_changelog
would result in Gitaly using the new approach.
Edited by Yorick Peterse