Implement SQLx interface

[halvardssm]

Relates to #167

Refactores the MySQL client to conform to the SQLx interfaces.

This introduces a breaking change to the usage, and should come with a breaking change release.

The following changes has been made:

• Added deno.json
• Implemented JSR deployment and support, and removed nest
• Added docker compose for the different test databases (all currently supported versions of MySQL and mariadb)
• Refactored auth plugin
• Refactored folder structure (src to lib, and moved code around)
• Refactored connection, client and pool
• Refactored logger