Receive touch mode state from WindowManager

Input needs to keep a copy of the touch mode state in order to tell apps
about it. The state will be sent to apps at the same time as the focus
change event.

The code currently does nothing, but the state will be needed in a
future CL.

Bug: 70668286
Test: presubmit
Change-Id: Ifab76977a0380370a753294d5a7504e3cec88af1