OverlayManager refactor and Flash (#1218)

* Flash component, overlay and shader
Add BeginDraw method to Overlay.cs

* Add flash icons, sounds

* Progress

* Multiple overlays without enums

* This is probably the worst way to do this IDK

* Remove nullable reference type

* Add AttackEventArgs as parameter to OnHitEntities
MeleeWeaponComponent.Attack now continues when OnHitEntities returns true (it hit something)
Add OverlayType enum so client and server can agree on overlay ids
Move IConfigurable to its own file
Add AoE flash with shorter duration
Flashing someone slows them down

* Add arc to flash
Set item size to something reasonable
Remove chat log message when flash burns out

* Remove unused interface

Content.Server/GameObjects/Components/Weapon/Melee/MeleeWeaponComponent.cs

@@ -81,9 +81,9 @@ namespace Content.Server.GameObjects.Components.Weapon.Melee
             serializer.DataField(ref _cooldownTime, "cooldownTime", 1f);
         }
 
-        public virtual bool OnHitEntities(IReadOnlyList<IEntity> entities)
+        protected virtual bool OnHitEntities(IReadOnlyList<IEntity> entities, AttackEventArgs eventArgs)
         {
-            return false;
+            return true;
         }
 
         void IAttack.Attack(AttackEventArgs eventArgs)
@@ -112,7 +112,7 @@ namespace Content.Server.GameObjects.Components.Weapon.Melee
                 }
             }
 
-            if(OnHitEntities(hitEntities)) return;
+            if(!OnHitEntities(hitEntities, eventArgs)) return;
 
             var audioSystem = EntitySystem.Get<AudioSystem>();
             var emitter = hitEntities.Count == 0 ? eventArgs.User : hitEntities[0];