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