Make Disarm opt-in (#7811)

Content.Shared/CombatMode/SharedCombatModeComponent.cs

@@ -30,6 +30,9 @@ namespace Content.Shared.CombatMode
         [DataField("disarmActionId", customTypeSerializer:typeof(PrototypeIdSerializer<EntityTargetActionPrototype>))]
         public readonly string DisarmActionId = "Disarm";
 
+        [DataField("canDisarm")]
+        public bool CanDisarm;
+
         [DataField("disarmAction")] // must be a data-field to properly save cooldown when saving game state.
         public EntityTargetAction? DisarmAction;