Zombie Rework & Polymorph Expansion (#8413)

Co-authored-by: Kara <lunarautomaton6@gmail.com>
Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

Content.Server/Disease/Effects/DiseaseAddComponent.cs

@@ -0,0 +1,30 @@
+using JetBrains.Annotations;
+using Content.Shared.Disease;
+
+namespace Content.Server.Disease.Effects
+{
+    /// <summary>
+    /// Adds a component to the diseased entity
+    /// </summary>
+    [UsedImplicitly]
+    public sealed class DiseaseAddComponent : DiseaseEffect
+    {
+        /// <summary>
+        /// The component that is added at the end of build up
+        /// </summary>
+        [DataField("comp")]
+        public string? Comp = null;
+
+        public override void Effect(DiseaseEffectArgs args)
+        {
+            if (Comp == null)
+                return;
+
+            EntityUid uid = args.DiseasedEntity;
+            var newComponent = (Component) IoCManager.Resolve<IComponentFactory>().GetComponent(Comp);
+            newComponent.Owner = uid;
+            if (!args.EntityManager.HasComponent(uid, newComponent.GetType()))
+                args.EntityManager.AddComponent(uid, newComponent);
+        }
+    }
+}