Problem: django.setup is an inconvenience for developers

[sevein]

a3m inherits from Archivematica's codebase the dependency on Django. The latter needs to be started manually before using it, so Django can populate its application registry. a3m implementors expect to include the following code in their applications:

from a3m.cli.common import init_django
init_django()

We want to hide this from implementors. init_django should become a no-op and be deprecated. The use of init_django should be removed from the examples (https://github.com/artefactual-labs/a3m/blob/main/examples/webapp.py) and docs (if there is any reference).