include additional flags for mysqldump action

Hello,

This is a feature request for the "mysqldump" charm action. Right now, it only includes the following flags by default:

 --triggers --routines --events

It's typically suggested to dump innodb databases with the "--single-transaction" flag[1], and those docs also suggest the "--quick" flag[2] as well (for large tables, anyway). To reduce impact, it might also be useful to include "--no-lock-tables"[3].

Just opening this report to start discussion around possibly including these as defaults, or maybe adding them as optional params to the action?

Thanks!

[1] https://dev.mysql.com/doc/refman/8.0/en/mysqldump.html#option_mysqldump_single-transaction
[2] https://dev.mysql.com/doc/refman/8.0/en/mysqldump.html#option_mysqldump_quick
[3] https://dev.mysql.com/doc/refman/8.0/en/mysqldump.html#option_mysqldump_lock-tables