mgr/dashboard: rgw role listing

mgr/dashboard: rgw role listing

Listing is performed using the radosgw-admin command api we have with
the mgr for now until the S3 api is fixed: https://tracker.ceph.com/issues/58547.

This commit fixes and issue with regards to the _crud.py controller
where redefining `CRUDClassMetadata` caused the users table and the
roles table to share columns. We fixed this by creating
CRUDClassMetadata dynamically for each endpoint.

The issue described above is linked to an issue with NamedTuple were
default nested lists are not a great move because it can cause
unexpected issues when 2 or more classes are created. Moreover,
NamedTuples are read-only making initialization even harder without
factory methods as with dataclasses. Therefore, let's move to the good
old __init__ :).

Signed-off-by: Pere Diaz Bou <pdiazbou@redhat.com>
Fixes: https://tracker.ceph.com/issues/58699