Add RECEIVER_NOT_EXPORTED to TV PiP broadcast receiver

Not explicitly adding this flag causes a SecurityException when PiP is
entered.

Bug: 269101156
Test: manual - start a PiP -> no crash, double press home -> PiP menu opens, click on PiP notificaation -> PiP goes back to fullscreen

Change-Id: I3c1f657de191343f3a33d3f4a9cf13467ff83f4b

libs/WindowManager/Shell/src/com/android/wm/shell/pip/tv/TvPipController.java

@@ -740,7 +740,7 @@ public class TvPipController implements PipTransitionController.PipTransitionCal
             if (mRegistered) return;
 
             mContext.registerReceiverForAllUsers(this, mIntentFilter, SYSTEMUI_PERMISSION,
-                    mMainHandler);
+                    mMainHandler, Context.RECEIVER_NOT_EXPORTED);
             mRegistered = true;
         }