Move TileFireEvent to Shared (#41285)

* Move to shared

* cleanup

---------

Co-authored-by: ArtisticRoomba <145879011+ArtisticRoomba@users.noreply.github.com>

Content.Shared/Atmos/TileFireEvent.cs

@@ -0,0 +1,10 @@
+namespace Content.Shared.Atmos;
+
+/// <summary>
+/// Event raised on an entity when it is standing on a tile that's on fire.
+/// </summary>
+/// <param name="Temperature">Current temperature of the hotspot this entity is exposed to.</param>
+/// <param name="Volume">Current volume of the hotspot this entity is exposed to.
+/// This is not the volume of the tile this entity is on.</param>
+[ByRefEvent]
+public readonly record struct TileFireEvent(float Temperature, float Volume);