Add a FF release process similar to the main gitlab project

Summary

As briefly discussed in !683 (comment 995775706), would be nice to have some sort of a process to monitor/release feature flags, similar to what we have in the main gitlab project https://docs.gitlab.com/ee/development/feature_flags/.

What I envision is some sort of a CI job that enforce a new issue for any new feature flag, this could run only if internal/feature/feature.go changes.