WIP add mysql support

[ezra-chu]

No description provided.

[Crim]

Thanks for the contribution! I have the following questions/notes:

• Do you know if it's possible to not include the MySQL client library in the POM, but instead have it available on the classpath?
  • I'm not sure if that will work, but if it does -- it may be a more sustainable path forward for supporting alternative datasources (PSQL, etc..) w/o having to package every client library w/ the release artifact.
• Ideally some way to perform automated testing using MySQL backed data store to ensure compatibility moving forward
  • This may require CI pipeline changes? Unsure exactly the best approach here.
• Updating/creating documentation outlining how to configure the service from the default of using it's internal H2 database to using an external MySQL instance. (How To style documentation)

Thanks!