Alert on manual action required
We support manual actions so jobs will only be triggered when a human manually goes into the GitLab interface to run them. We should support alerting people that a manual actions is ready to be run. Specifically, a manual action is often used to promote a release from staging to production, and is often done by a different person that the person that triggered the pipeline. We likely need to support alerting to the pipeline originator and/or to another set of people with permissions to perform the action. And this should probably be optional (per project or per job?). e.g. some organizations intend on running the job for every pipeline, but need a manual approval before doing so. But other pipelines might have a truly optional manual action that for which alerts would be noise.