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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 -->

if check_mode:
        return True
    if host_all:
        hostnames = user_get_hostnames(cursor, [user])
        for hostname in hostnames:
            cursor.execute("DROP USER %s@%s", (user, hostname))
    else:
        cursor.execute("DROP USER %s@%s", (user, host))
    return True
def user_get_hostnames(cursor, user):
    cursor.execute("SELECT Host FROM mysql.user WHERE user = %s", user)
    hostnames_raw = cursor.fetchall()
    hostnames = []
    for hostname_raw in hostnames_raw:
        hostnames.append(hostname_raw[0])
    return hostnames
def privileges_get(cursor, user, host):