- drop jQuery and fontawesome dependencies
- add bootstrap5 and bootstrap-icons
- update fonts mfizz
- update base templates and the first set of other templates
- replace blocktrans and trans with blocktranslate and translate to
prepare for Django 4
- move hostingpakcage templates to hostingpackages/templates
- update translations
- use signals to trigger Celery tasks to create and delete mailboxes
- add generic TestCaseWithCeleryTasks class to handle celery task tests
in a uniform way
- don't execute celery tasks directly
- introduce optional parameters to fileserver tasks to allow chaining
- handle user/group/key create and delete tasks in new osusers.signals
class
- adapt unit tests
- change TaskResults model to store the task signatures
- generalize the local settings' logging configuration
