No position information for outside touches

When a window registers to listen for outside touches, it doesn't need
the position information for touches that land outside of its activity
for normal use cases.

This patch uses the foreground window's UID as a filter to determine
whether to pass the position information. This will allow applications
to continue to rely on touch information for inputs that were directed
at one of its other windows.

Bug: 4541250
Change-Id: If16eb1ec8404b797d991859eef55ac0a20a355a3