Add functionality to mariadb-admin to manipulate catalogs

The mariadb-admin tool can be used to create and drop databases. This should be a good place to create and drop catalogs.

The commands for this should probably be "create-catalog" and "drop-catalog" to distinguish between the current "create" and "drop" from databases.

Implementing create-catalog in mariadb-admin can be done by having mariadb-admin call mariadb-install-db --catalogs=<catalog>.

drop-catalog can be done just by issuing DROP CATALOG to the Server