Improve CompatMgr behaviour for unknown versions

[miniduikboot]

Description

Currently, Impostor will show an "Client is in an invalid state." message if a player tries to join a match where the host or the joining player is using a version unknown to Impostor.

This message confused a lot of people, so this PR changes the API such that if the version is not registered, the version itself is put in a compatibility group and compared, assuming no other game versions are compatible with it. This works fine in most cases, as Among Us network versions generally increase over time.

Failure on 2222.2.2 (which is ancient at this point, so likely no longer used) and future cases where Innersloth messes up (which is unlikely) is an acceptable consequence to me.