ECS StunnableProjectile (#4309)

* ECS StunnableProjectile

Also renamed it to the more generic component for stunning on collision

* Reviews

Content.Server/Stunnable/Components/StunOnCollideComponent.cs

@@ -0,0 +1,23 @@
+using Robust.Shared.GameObjects;
+using Robust.Shared.Serialization.Manager.Attributes;
+
+namespace Content.Server.Stunnable.Components
+{
+    /// <summary>
+    /// Adds stun when it collides with an entity
+    /// </summary>
+    [RegisterComponent]
+    internal sealed class StunOnCollideComponent : Component
+    {
+        // TODO: Can probably predict this.
+        public override string Name => "StunOnCollide";
+
+        // See stunnable for what these do
+        [DataField("stunAmount")]
+        internal int StunAmount = default;
+        [DataField("knockdownAmount")]
+        internal int KnockdownAmount = default;
+        [DataField("slowdownAmount")]
+        internal int SlowdownAmount = default;
+    }
+}