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##### SUMMARY
<!--- Describe the new feature/improvement briefly below -->
New Percona/MySQL 8 privileges with underscore is not working. 
the following error is coming 

`MSG: invalid privileges string: Invalid privileges specified: frozenset({'BACKUP_ADMIN'})`

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
mysql_user module
most likely the new privileges needs to be added to lib/ansible/modules/database/mysql/mysql_user.py

##### ADDITIONAL INFORMATION
<!--- Describe how the feature would be used, why it is needed and what it would solve -->

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

```

<!--- HINT: You can also paste gist.github.com links for larger files -->

db_table = db_table.replace('%', '%%')
    priv_string = ",".join([p for p in priv if p not in ('GRANT', 'REQUIRESSL')])
    query = ["GRANT %s ON %s" % (priv_string, db_table)]
    query.append("TO %s@%s")
    if 'REQUIRESSL' in priv:
        query.append("REQUIRE SSL")
    if 'GRANT' in priv:
        query.append("WITH GRANT OPTION")
    query = ' '.join(query)
    cursor.execute(query, (user, host))
def convert_priv_dict_to_str(priv):
    """Converts privs dictionary to string of certain format.
    Args:
        priv (dict): Dict of privileges that needs to be converted to string.
    Returns:
        priv (str): String representation of input argument.
    """
    priv_list = ['%s:%s' % (key, val) for key, val in iteritems(priv)]
    return '/'.join(priv_list)
#
def main():