Unreviewed, fix the internal build after 265828@main

Replace `WTF::UUID` with `UUID` in this Swift file, since `UUID` here just refers to `NSUUID`.

* Source/WebKit/UIProcess/Cocoa/GroupActivities/WKGroupSession.swift:
(WKGroupSessionWrapper.uuid):

Canonical link: https://commits.webkit.org/265840@main

Source/WebKit/UIProcess/Cocoa/GroupActivities/WKGroupSession.swift

@@ -68,7 +68,7 @@ public final class WKGroupSessionWrapper : NSObject {
     }
 
     @objc public var activity: WKURLActivityWrapper { self.activityWrapper }
-    @objc public var uuid: WTF::UUID { groupSession.id }
+    @objc public var uuid: UUID { groupSession.id }
 
     private static func wrapperSessionState(state: GroupSession<URLActivity>.State) -> WKGroupSessionState {
         switch state {