to suit upcoming work for mariadb-backup with galera which will require new system accounts, as well as to potentially suit the use case of mariadb root password rotation, a new mode of operation will be added to the MariaDBAccount CR and operators, which allows the management of MariaDBAccount objects that are not tied to a specific MariaDBDatabase and are instead system wide.

These MDB accounts will differ from the existing ones in the following ways:

1. There will be no MariaDBDatabase associated with such a MariaDBAccount, they are only associated with a Galera instance
2. They will support application of their username/password towards a particular galera instance that itself has not been installed or bootstrapped yet, instead assigning the new account information to be created in the container init phase.  
3. It will be possible for the galera operator itself to be dependent on such MariaDBAccount having set up its account creation before the galera operator actually installs the DB, that is galera operator can block until mariadbaccount has set up what it needs to generate for example a "root" account
4. The MariaDBAccount also can be created and manipulated for a galera that's already running, supporting the creation of new mariadbaccount objects and dropping them also (minus the root account)
5. for root account at least, the new CR should support in-place password changes where the username does not change; instead, the MariaDBAccount will be able to accommodate being associated with a new secret which will update at once