Fire MeleeHitEvent on misses. (#12867)

* Fire MeleeHitEvent when there are no targets.

* Prevent certain weapons from activating if they had no hit entities on hit.

* Prevent miss events from firing when target is yourself or was deleted.

* Use .Value as Target is already known not to be null.

* uid changes

---------

Co-authored-by: metalgearsloth <comedian_vs_clown@hotmail.com>

Content.Shared/Weapons/Melee/Events/MeleeHitEvent.cs

@@ -12,7 +12,7 @@ public sealed class MeleeHitEvent : HandledEntityEventArgs
     /// <summary>
     ///     The base amount of damage dealt by the melee hit.
     /// </summary>
-    public readonly DamageSpecifier BaseDamage = new();
+    public readonly DamageSpecifier BaseDamage;
 
     /// <summary>
     ///     Modifier sets to apply to the hit event when it's all said and done.
@@ -31,18 +31,18 @@ public sealed class MeleeHitEvent : HandledEntityEventArgs
     /// <summary>
     ///     A list containing every hit entity. Can be zero.
     /// </summary>
-    public IEnumerable<EntityUid> HitEntities { get; }
+    public IReadOnlyList<EntityUid> HitEntities;
 
     /// <summary>
     ///     Used to define a new hit sound in case you want to override the default GenericHit.
     ///     Also gets a pitch modifier added to it.
     /// </summary>
-    public SoundSpecifier? HitSoundOverride {get; set;}
+    public SoundSpecifier? HitSoundOverride;
 
     /// <summary>
     /// The user who attacked with the melee weapon.
     /// </summary>
-    public EntityUid User { get; }
+    public readonly EntityUid User;
 
     /// <summary>
     /// Check if this is true before attempting to do something during a melee attack other than changing/adding bonus damage. <br/>
@@ -59,4 +59,4 @@ public sealed class MeleeHitEvent : HandledEntityEventArgs
         User = user;
         BaseDamage = baseDamage;
     }
-}
+}