Introduce new portal window which transports touch to another display

It enables the user to directly touch on a window of a display
embedded on another one. The embedded displays can be nested.

The monitoring channels of the embedded display can also receive touch
events.

Bug: 120675821
Test: Manual test with ActivityViewTest
Test: atest -a inputflinger_tests
Test: atest CtsActivityManagerDeviceTestCases:ActivityViewTest
Change-Id: I773c7efb1b048080020aadd45156261a10095fcb
diff --git a/include/input/InputWindow.h b/include/input/InputWindow.h
index 2b8cc57..a065a4c 100644
--- a/include/input/InputWindow.h
+++ b/include/input/InputWindow.h
@@ -163,6 +163,7 @@
     int32_t ownerUid;
     int32_t inputFeatures;
     int32_t displayId;
+    int32_t portalToDisplayId = ADISPLAY_ID_NONE;
     InputApplicationInfo applicationInfo;
 
     void addTouchableRegion(const Rect& region);