explosion minor rework + fix (#21718)

Content.Shared/Storage/Components/SharedEntityStorageComponent.cs

@@ -124,6 +124,12 @@ public abstract partial class SharedEntityStorageComponent : Component
     /// </summary>
     [ViewVariables]
     public Container Contents = default!;
+
+    /// <summary>
+    /// Multiplier for explosion damage that gets applied to contained entities.
+    /// </summary>
+    [DataField]
+    public float ExplosionDamageCoefficient = 1;
 }
 
 [Serializable, NetSerializable]