Fixed potential infinite recursion `ISyncSimple` crashes

[SokyranTheDragon]

Calls to SyncSerialization.CanHandle can cause a crash due to infinite recursion when used with a subtype of ISyncSimple.

The crash would happen when a subtype of ISyncSimple would have a ISyncSimple field. The CanHandle checks all fields of a type implementing ISyncSimple, as well as all its subtypes, to see if they can be synced. However, as it encounters ISyncSimple during the check, it would then check if it can sync ISyncSimple, which would then check if it can sync ISyncSimple again and again until a crash.

I've originally attempted to fix this by modifying the conditions to skip in specific situations, like the type being an interface, or for recursively checking subtypes of self, etc. - this ended up very messy, and I would just end up finding another example that would cause a crash. I've opted out for this solution as it should handle all of the weird edge cases we may encounter.

Some simple examples of types that would cause a crash:

class TestSync : ISyncSimple
{
    ISyncSimple test;
}

class TestSync : ISyncSimple
{
    List<ISyncSimple> test;
}