Updates to background tasks

[torgeirl]

Issues

• failure handling for background tasks seem to need a re-work since tasks that failed due to errors such as #1292 don't get listed in the Django Admin UI (should have been listed, and with Status=Error)
• we need support tor TLS communication between Gunicorn/RQ worker and the Redis server. Redis v6 introduced SSL/TLS support so it looks like this will require Devilry's dependencies to be updated to work with redis-py 4.0.0+?
• we need support for Redis Sentinel

Suggested solution

• Update rq, django-rq and redis dependencies to releases that support Redis server somewhere from 6.0 (first with TLS support) to 7.2.4 (last Redis release under an open source license)
• do adjustments for Devilry and its RQ Worker to work with Redis Sentinel (if any)
• improve how the background process handles errors
• improve or remove utils/rq_setup.py (no longer needed?)
• update RQ docs accordingly

What versions should we aim for

• redis 5.0.0+ supports Redis server 5.0 to 7.2+ while 4.5.0+ supports Redis server 5.0-7.0
• rq 1.15 requires redis 4.0.0+, but due to changes with how its errors are captured by Sentry with probably want 1.16
• django-rq 2.8.1 requires rq 1.14+ (and 2.8.0 added support for USERNAME and SENTINEL_KWARGS)

So perhaps redis==5.0.*+ rq==1.16.* + django-rq==2.8.* is an OK place to start while we are on Django 4.2?

[espenak]

Only missing some updates to the rq_setup module - need to update it or just document how to setup manually

[espenak]

I just kept the quick setup module (rq_setup), but updated the docs for RQ setup with hints for more complex setups like sentinel and https.