For new cloudrons this will first remove the previously added group and
mailbox entry from the db migration scripts and readds it once we have a
domain on owner creation
This adds domains table and adjusts the apps and mailboxes table accordingly
Also ensure we explicitly set the table collation, this is required
for the foreign key from apps table (utf8) and the newly created
domains table, which by default now would be utf8mb4
Put db table constraint for mailboxes.domain
Update the schema file