Add test class to ensure that version specific features have still not been implemented yet

[lauxjpn]

The ServerVersionSupport derived classes of MySqlServerVersionSupport and MariaDbServerVersionSupport are heavily used internally to determine which features are available and what syntax to use for them.

We current do not check whether a once unavailable/not implemented feature became available/was implemented in the meantime in a newer database engine version.

We should add a test class for that (or one for each officially supported database engine), so that we get a failed test, once a feature becomes available, which would then prompt us to look into that change.