cephadm: Ensure wildcard SAN is included in RGW self-signed certs

cephadm: Ensure wildcard SAN is included in RGW self-signed certs

Fix:
- Updated `RgwService` in `cephadmservice.py` to append `*.` before each hostname
  in `zonegroup_hostnames` when generating certificates if wildcard_enabled flag is set to true.
- This ensures that both the entries including the wildcard entry (example: 's3.cephlab.com' and '*.s3.cephlab.com') are included in the SAN.
- After this fix, virtual host bucket access works without SSL errors.

Signed-off-by: Kushal Deb <Kushal.Deb@ibm.com>