Add support for celery workers

[davidban77]

Environment

• Nautobot version: ^1.3

Proposed Functionality

Nautobot has changed to use celery workers instead of rq workers

[Kircheneer]

Superseded by this: nautobot/nautobot#3045?

[Kircheneer]

In a similar manner, now that Nautobot 2.0 is dropping RQ as a dependency (even though it hadn't been used anyway) we should delete anything RQ inside of this plugin.