Change battle actions to use battle decisions instead.

battle/action/BattleDecision.gd

@@ -0,0 +1,13 @@
+class_name BattleDecision
+
+var action:BattleAction
+var user:BattleFighter
+var target:BattleFighter
+
+func _init(_action:BattleAction, _user:BattleFighter, _target:BattleFighter) -> void:
+  action = _action
+  user = _user
+  target = _target
+
+func getPriority() -> float:
+  return 1.0