Alt Toggle for Custom animation (#6433)

Add explicit alt prefix checking to animation loading

Makes ResourceMgr_LoadAnimByName alt-toggleable this will work for Link and any other animations files

soh/src/code/z_skelanime.c

@@ -902,6 +902,10 @@ void AnimationContext_SetLoadFrame(PlayState* play, LinkAnimationHeader* animati
         if (frame < 0) {
             frame = 0;
         }
+        // SOH [Alt Assets] Check if animData is null (can happen if animation data segment failed to load)
+        if (animData == NULL) {
+            return;
+        }
         memcpy(ram, (uintptr_t)animData + (((sizeof(Vec3s) * limbCount + 2) * frame)), sizeof(Vec3s) * limbCount + 2);
     }
 }