Rework authentication for local Cloud/Collab development (#35450)

This PR reworks authentication for developing Zed against a local
version of Cloud and/or Collab.

You will still connect the same way—using the `zed-local` script—but
will need to be running an instance of Cloud locally.

Release Notes:

- N/A
09b93caa9bMarshall Bowers committed on 8/1/2025, 12:55:17 AM· committed by GitHubparent7c169fc
3 files changedLine totals unavailable