Moves VM autobackups from being in-CLI to being handled by the
pvcworkerd system on the primary coordinator. Turns the CLI autobackup
command into an actual API client endpoint rather than having its logic
in the CLI.
In addition, modifies the new autobackup to leverage the new "pvc vm
snapshot" function set, just with special snapshot names. This helps
automate this within the new snapshot scaffolding.
Moves all tasks run by the Celery worker into a discrete package/module
for easier installation. Also adjusts several parameters throughout to
accomplish this.
