Implement Migrate for MySQL

[KyleJune]

I wrote this module with the intent for it to later be extended for other databases besides Postgres. The CLI and basic script should work with any Migrate object. If any additional code from PostgresMigrate can be moved to Migrate for re-use in MySQLMigrate, move it while working on it. We may want to move some of the code related to locking to the base class.

[KyleJune]

I don't personally have a need for MySQL migration support so I'm not sure when I would get around to implementing this. If there is a lot of demand for it, I can do that. If anyone wants to take this task on I would be open to merging as long as there is good test coverage. To add it, you would need to update docker to have a mysql service. The quickest way to implement MySQLMigrate would be to copy postgres.ts and postgres_test.ts then adapt those copies to use mysql.