Remove ICollideSpecial

Handled in an ECS way by PreventCollideEvent.
The disposals one doesn't work anyway and would've required a larger refactor of disposals to fix so out of scope.

Content.Shared/GameObjects/EntitySystems/ProjectileSystem.cs

@@ -0,0 +1,24 @@
+using Content.Shared.GameObjects.Components.Projectiles;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Physics.Dynamics;
+
+namespace Content.Shared.GameObjects.EntitySystems
+{
+    public sealed class ProjectileSystem : EntitySystem
+    {
+        public override void Initialize()
+        {
+            base.Initialize();
+            SubscribeLocalEvent<SharedProjectileComponent, PreventCollideEvent>(PreventCollision);
+        }
+
+        private void PreventCollision(EntityUid uid, SharedProjectileComponent component, PreventCollideEvent args)
+        {
+            if (component.IgnoreShooter && args.BodyB.Owner.Uid == component.Shooter)
+            {
+                args.Cancel();
+                return;
+            }
+        }
+    }
+}