ksys: Forward declare Actor where possible

Reduces build times when Actor.h is modified.

src/KingSystem/Quest/qstStep.cpp

@@ -1,5 +1,6 @@
 #include "KingSystem/Quest/qstStep.h"
 #include <memory>
+#include "KingSystem/ActorSystem/actActor.h"
 #include "KingSystem/Quest/qstActorData.h"
 #include "KingSystem/Quest/qstIndicator.h"
 

src/KingSystem/Quest/qstStep.h

@@ -2,12 +2,16 @@
 
 #include <container/seadObjArray.h>
 #include <container/seadPtrArray.h>
-#include "KingSystem/ActorSystem/actActor.h"
+#include <prim/seadSafeString.h>
 #include "KingSystem/ActorSystem/actBaseProcLink.h"
 #include "KingSystem/GameData/gdtFlagHandle.h"
 #include "KingSystem/Utils/Byaml/Byaml.h"
 #include "KingSystem/Utils/Types.h"
 
+namespace ksys::act {
+class Actor;
+}
+
 namespace ksys::qst {
 
 struct ActorData;