mgr/cephadm: pass RGW zonegroup hostnames as custom SANs

mgr/cephadm: pass RGW zonegroup hostnames as custom SANs

Fix RGW certificate generation so `zonegroup_hostnames` and wildcard
SANs are passed to `get_certificates()` using the correct keyword
argument. Previously, RGW built the expected SAN list from
`zonegroup_hostnames` and `wildcard_enabled`, but passed it
positionally so it was interpreted as ips list.

Also add a unit test to cover the RGW `zonegroup_hostnames` +
`wildcard_enabled` path and ensure SANs are passed as `custom_sans`.

Fixed other calls to enforce the usage of keywords for arguments just
to avoid similar issues in the future.

Fixes: https://tracker.ceph.com/issues/77980
Signed-off-by: Redouane Kachach <rkachach@ibm.com>