After settings rework, we decided to make the upgrade plug-ins define their own configuration types. This is basically the definition for these configuration types. Only the get_version function is not yet implemented.
Contributes to issue CURA-844.
This plug-in does nothing at the moment. It merely says that it is able to upgrade configuration from version 2.1 to 2.2, but then raises exceptions when you actually try to use it. This is by design. I will now implement the functions that do the conversion.
Contributes to issue CURA-844.
