Try to explicitly handle env_sprite(trail)

This should work as a generic way to handle any entity classes that are parented in-engine, but it'll only be applied to env_sprite/env_spritetrail for now unless we come across more entities that behave this way.

Update contraption_sv.lua

Add ContainsClass

Move this into classes; see why in desc

We don't want hooks erroring this out
We want hooks to be able to have access to this data

So if we do an extension, we lose that ability...

Fix function

Didn't check for PreParented here

Try improving CFW parenting a little, new hooks

CFW_AfterParentedTo -> CFW_OnParentedTo

CFW rename: CFW_OnParentedTo -> CFW_PreParentedTo

Try to fix a potential parenting error