UX: Warn when changing category to the Schedule Publishing target (PR #12134)

This is a client-side block only; bulk category changes and API clients can still move shared drafts around. I chose to allow that in order to make sure it was possible to recover from broken shared draft metadata.

Additionally, moving a shared draft into the proper category is allowed by the client.

No tests because writing UI tests is still a bad time.

GitHub

The title of this pull request changed from “UX: Block attempts to move a shared draft outside the drafts category” to "UX: Warn when changing category to the Schedule Publishing target

I am not sure I agree with this, this seems like busywork to me:

Please do random work to make this work

Instead we should just handle the punches as they come. Abort the save and error, or fix the situation on save.