Added the concept of "ClassTypeActions" for class asset types (C++ classes and Blueprints)
UE-7970 - Add small 'play' button to EditorTutorial asset thumbnail
Class asset types (C++ classes and Blueprints) are now able to provide actions that should be performed based upon the type of class the asset contains, rather than the asset class itself (which is always "Class" or "Blueprint").
This will allow the editor tutorials to provide class type actions for Blueprints that derive from "EditorTutorial" without requiring this information to be put into the asset type actions for Blueprint assets.
ReviewedBy Thomas.Sarkanen
[CL 2419736 by Ben Marsh in Main branch]