previews: GHA bot comment with deployment status #387
Description
https://fluxcd.io/flux/components/notification/providers/#github-dispatch into a github actions workflow that leaves a comment, with https://fluxcd.io/flux/components/notification/alerts/ to feed it events from the preview objects.
For the first pass, just have the workflow log the payload and then exit, to work out what information is actually in there.
Have each preview include its own Alert object with metadata that links it to the PR.
Like in https://flux-iac.github.io/tofu-controller/use-tf-controller/flux-receiver-and-alert/, patch out the kind enum in the Alert CRD and add RBAC for the extra objects.