genericize ui fragments (#12810)

Content.Client/UserInterface/Fragments/UiFragmentComponent.cs

@@ -0,0 +1,15 @@
+namespace Content.Client.UserInterface.Fragments;
+
+/// <summary>
+/// The component used for defining a ui fragment to attach to an entity
+/// </summary>
+/// <remarks>
+/// This is used primarily for PDA cartridges.
+/// </remarks>
+/// <seealso cref="UIFragment"/>
+[RegisterComponent]
+public sealed class UIFragmentComponent : Component
+{
+    [DataField("ui", true)]
+    public UIFragment? Ui;
+}