oradb-manage-db: Support for oracle_db_instance_name in oracle_databases
oradb-manage-db: Support for oracle_db_instance_name in oracle_databases

The support for a dedicated instance_name during database creation
was missing for the role oradb-manage-db.

ilspleno/ansible-oracle,ilspleno/ansible-oracle,oravirt/ansible-oracle,oravirt/ansible-oracle