Adds Hellspawn (Nar'Sie demon mob) (#20291)

* HellSpawn Mob

* added spawner

* summary for the namespace

* larger collider, cannot enter single tile corridors.

* fix

* remove duplicate from yml, fix attributions.

* moved action to shared, moved comp to shared, networked comp, separated heal, fixed attributions

* removed flammable from hellspawn
removed the healing effect from firestarter ability (healing can be separate ability).

* Update attributions.yml

fix attributions

* fix

* fix

Content.Shared/Actions/Events/FireStarterActionEvent.cs

@@ -0,0 +1,10 @@
+namespace Content.Shared.Actions.Events;
+
+public sealed partial class FireStarterActionEvent : InstantActionEvent
+{
+    /// <summary>
+    /// Increases the number of fire stacks when a flammable object is ignited.
+    /// </summary>
+    [ViewVariables(VVAccess.ReadWrite)]
+    public float Severity = 0.3f;
+}