mgr/dashboard: Bucket names cannot be formatted as IP address

mgr/dashboard: Bucket names cannot be formatted as IP address

In general, bucket names should follow domain name constraints:
- Bucket names must be unique.
- Bucket names cannot be formatted as IP address.
- Bucket names can be between 3 and 63 characters long.
- Bucket names must not contain uppercase characters or underscores.
- Bucket names must start with a lowercase letter or number.
- Bucket names must be a series of one or more labels. Adjacent labels are separated by a single period (.). Bucket names can contain lowercase letters, numbers, and hyphens. Each label must start and end with a lowercase letter or a number.

Fixes: https://tracker.ceph.com/issues/42069
Signed-off-by: Volker Theile <vtheile@suse.com>