Automatically set code owner for celery tasks

[robrap]

This is a possible on-call improvement so that we don't need to add custom code to each celery task to get its code owner marked.

This was tried in openedx/edx-platform#33179, but it didn't work for New Relic instrumentation. It may be that Datadog is using the signals, and this might possibly work.

Related, the community probably doesn't care about codeowner, but 2U doesn't yet have its own universal 2u-django-utils.

[robrap]

If this code is only used by 2U in a plugin, we could try the signal handler, but could also potentially use Datadog's span creation callbacks that we've used for other diagnostics.

Note: This is related to our ability to potentially DEPR all the codeowner code.

• See DEPR and move code owner monitoring code with updates #784