Co-Op mode incompatible with Important Checks Mode

[zax-xyz]

Co-Op mode is only implemented for the "standard" tracker and does not work with KH2 Important Checks Mode (KH2_IC). This includes the "remote" feature.

There shouldn't need to be any changes made to the backend, as we just need to create new types of messages, which are defined in the frontend and passed through directly by the server without any modifications or internal state other than room management.