##### SUMMARY
mysql_db module should be able to create/drop multiple databases

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
lib/ansible/modules/database/mysql/mysql_db.py

##### ADDITIONAL INFORMATION
Why and what it would solve:
Avoids repetitive tasks to create/delete more than one databases (similar to https://github.com/ansible/ansible/issues/56059)

<!--- Paste example playbooks or commands between quotes below -->

- Create (Multiple databases)
```yaml
  tasks:
  - name: Create multiple databases (provided in comma separated form)
    mysql_db:
      name: bobdata, bobthebuilder
      state: present
  - name: Create multiple databases (provided in list form)
    mysql_db:
      name:
        - bobdata
        - bobthebuilder
      state: present
```

- Delete/Drop (Multiple databases)
```yaml
  - name: Delete/drop multiple databases (provided in comma separated form)
    mysql_db:
      name: bobdata, bobthebuilder
      state: absent
  - name: Delete/drop multiple databases (provided in list form)
    mysql_db:
      name:
        - bobdata
        - bobthebuilder
      state: absent
```

Credits for the idea to @Andersson007 from comment https://github.com/ansible/ansible/pull/56721#issuecomment-505128646
db = ['mysql']
            all_databases = True
        else:
            all_databases = False
    else:
        if db == ['all']:
            module.fail_json(msg="name is not allowed to equal 'all' unless state equals import, or dump.")
    try:
        cursor = mysql_connect(module, login_user, login_password, config_file, ssl_cert, ssl_key, ssl_ca,
                               connect_timeout=connect_timeout)
    except Exception as e:
        if os.path.exists(config_file):
            module.fail_json(msg="unable to connect to database, check login_user and login_password are correct or %s has the credentials. "
                                 "Exception message: %s" % (config_file, to_native(e)))
        else:
            module.fail_json(msg="unable to find %s. Exception message: %s" % (config_file, to_native(e)))
    changed = False
    if not os.path.exists(config_file):
        config_file = None
    if db_exists(cursor, db):
        if state == "absent":
            if module.check_mode:
                module.exit_json(changed=True, db=db_name)
            try:
                changed = db_delete(cursor, db)
            except Exception as e:
                module.fail_json(msg="error deleting database: %s" % to_native(e))
            module.exit_json(changed=changed, db=db_name)
        elif state == "dump":
            if module.check_mode: