Allow EmbeddedWindowController to transfer entire gesture

This is needed to maintain some of the previous behaviour that was
removed when splitting code was cleaned up.

Since this is part of the current API, we should maintain the behaviour
advertised by WindowManager::transferTouchGesture, until it's
deprecated.

Bug: 397979572
Test: TEST=inputflinger_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST
Flag: com.android.input.flags.allow_transfer_of_entire_gesture
Change-Id: Ifb9335041b7881d72f4b57a59b9aea281e28370f