Refactor Flammable to be ECS. (#4671)

- Refactor IHotItem into IsHotEvent.
- Refactor IFireAct into TileFireEvent.

Content.Server/Nutrition/EntitySystems/SmokingSystem.cs

@@ -0,0 +1,20 @@
+using Content.Server.Nutrition.Components;
+using Content.Shared.Smoking;
+using Content.Shared.Temperature;
+using Robust.Shared.GameObjects;
+
+namespace Content.Server.Nutrition.EntitySystems
+{
+    public class SmokingSystem : EntitySystem
+    {
+        public override void Initialize()
+        {
+            SubscribeLocalEvent<SmokingComponent, IsHotEvent>(OnIsHotEvent);
+        }
+
+        private void OnIsHotEvent(EntityUid uid, SmokingComponent component, IsHotEvent args)
+        {
+            args.IsHot = component.CurrentState == SharedBurningStates.Lit;
+        }
+    }
+}