Support requiring SSL, and verifying CA, for MySQL

[MatthiasKunnen]

This PR adds support for requiring a secure connection and man-in-the-middle protection in the form of the DBMATE_MYSQL_SSL_MODE and DBMATE_MYSQL_CA_PATH parameter.

• DBMATE_MYSQL_SSL_MODE is an implementation of https://dev.mysql.com/doc/refman/8.4/en/connection-options.html#option_general_ssl-mode
• DBMATE_MYSQL_CA_PATH implements https://dev.mysql.com/doc/refman/8.4/en/connection-options.html#option_general_ssl-ca

This PR will also fix tests failing on the main branch due to certificate verification problems.

Important caveat, the CLI parameter --ssl-mode used for mysqldump is not present in mariadb dump. If there is a way to detect whether mariadb-dump is used, I could change the parameters accordingly but there does not seem to be a distinction at the moment. Suggestions welcome.

I'll refrain from further work until there is some feedback on the approach and whether there is interest in this change.

Todo:

• Decide how to handle mariadb dump compatibility
• Add documentation

[dossy]

The change in #730 addresses very basic SSL on/off control for dbmate with MySQL and MariaDB. No support for CA certificates was implemented there.

Personally, my opinion is rather than trying to shoehorn a menagerie of configuration knobs onto dbmate, it would be far more useful to add a general-purpose "extra args" value that can be specified that is passed through to the underlying dump executable, then the dbmate user has full control now and in the future without additional changes to dbmate itself.

[dossy]

Also: it would be nice to better support CA certificate handling for SSL/TLS connections for all our drivers, not just MySQL. What I mean is, I would prefer a solution that was generalized at the interface level, and each driver implements the necessary mechanism to provide the functionality.