ksys: Merge EcoUtil into ActorUtil

The "is in Satori mountain area" function actually appears to be part
of ActorUtil (which contains a bunch of actor-related helper functions)

src/KingSystem/Ecosystem/CMakeLists.txt

@@ -3,6 +3,4 @@ target_sources(uking PRIVATE
   ecoLevelSensor.h
   ecoSystem.cpp
   ecoSystem.h
-  ecoUtil.cpp
-  ecoUtil.h
 )

src/KingSystem/Ecosystem/ecoUtil.cpp

@@ -1,9 +0,0 @@
-#include "KingSystem/Ecosystem/ecoUtil.h"
-
-namespace ksys::eco {
-
-bool currentAreaNumIs64(const sead::Vector3f& pos) {
-    return Ecosystem::instance()->getFieldMapArea(pos.x, pos.z) == 64;
-}
-
-}  // namespace ksys::eco

src/KingSystem/Ecosystem/ecoUtil.h

@@ -1,10 +0,0 @@
-#pragma once
-
-#include <math/seadVector.h>
-#include "KingSystem/Ecosystem/ecoSystem.h"
-
-namespace ksys::eco {
-
-bool currentAreaNumIs64(const sead::Vector3f& pos);
-
-}  // namespace ksys::eco