Cluster grenade refactor and contra markings (#31108)

* Cluster grenade refactor

* oopsies on the name

* Solve client-side errors

* reviews addressed

* filling scattering grenades is now predicted

* reviews addressed

Content.Shared/Damage/Systems/RequireProjectileTargetSystem.cs

@@ -34,6 +34,11 @@ public sealed class RequireProjectileTargetSystem : EntitySystem
             if (!shooter.HasValue)
                 return;
 
+            // ProjectileGrenades delete the entity that's shooting the projectile,
+            // so it's impossible to check if the entity is in a container
+            if (TerminatingOrDeleted(shooter.Value))
+                return;
+
             if (!_container.IsEntityOrParentInContainer(shooter.Value))
                args.Cancelled = true;
         }