Refactors flashes to ECS, sunglasses protect you from being flashed. (#4579)

* Refactors flashes to ECS, sunglasses protect you from being flashed.

* VV ReadWrite for FlashImmunity Enabled.

* Use cached IEntityLookup.

* Consistent formatting.

* Fix flashbang duration.
Flash duration is a mess.

* Small area flash code cleanup.

* Flashable state is only sent to attached player.

Content.Server/Explosion/Components/SoundOnTriggerComponent.cs

@@ -14,7 +14,7 @@ namespace Content.Server.Explosion.Components
         public override string Name => "SoundOnTrigger";
 
         [ViewVariables(VVAccess.ReadWrite)]
-        [DataField("sound", required: true)]
-        public SoundSpecifier Sound { get; set; } = default!;
+        [DataField("sound")]
+        public SoundSpecifier? Sound { get; set; }
     }
 }