Change battle actions to use battle decisions instead.

battle/action/BattleAction.gd

@@ -0,0 +1,11 @@
+class_name BattleAction
+
+var speedModifier:float
+
+func _init(params:Dictionary) -> void:
+  self.speedModifier = params.get("speedModifier", 1.0)
+
+func perform(params:Dictionary) -> void:
+  assert(params.has("user"))
+  assert(params.has("target"))
+  pass