Run tests with MySQL

[manuelma]

Not sure if we had an issue about this yet, but this is highly desirable.

[jkiviluo]

Someone could work on this (unless done already). @soininen @PiispaH?

[soininen]

Someone could work on this (unless done already).

I think the biggest hurdle is how to set up a MySQL server and manage credentials safely, especially when running tests as GitHub action.

It may be hard to catch some MySQL specific errors with testing, though. We have had some issues in the past which showed up on certain MySQL databases while not on others depending on specific database server configuration.

[jkiviluo]

Right, lot of work and we can survive without. I'll move this later.