ClassInjector.SystemTypeFromIl2CppType fails when types are prefixed.

[WNP78]

ClassInjector.SystemTypeFromIl2CppType finds types by querying IL2CPP for their full name and assembly name and then using the managed Type.GetType on a string constructed from it, which fails when they have the Il2Cpp prefix added to them. I made a hacky fix, which just tries adding Il2Cpp if it fails without it, but there should probably be a better way that somehow checks if it's being prefixed.