Please add Game-defined Effects slots, both Pre and Post the current User-defined effects
The current implementation of SetActorMixerEffect does not meet this need.
1) it requires the "Override Parent" setting to be enabled, which eliminates higher level ActorMixer User-defined effects
2) it overwrites 1 of the 4 slots, that might already be in use from a User-defined effect
3) it is not able to define effects before and/or after the User-defined effects
