Move focus dispatch to input (1/2)

Input now tells the apps when they have focus.
When a focus change has been detected, we enqueue a FocusEntry into the
dispatcher queue. It will be sent to the app via the socket.

At the same time, we tell the apps the current state of the touch mode.

Bug: 70668286
Test: atest libinput_tests inputflinger_tests
Change-Id: Icefb9383ba8424162d739c9e981bd1dd01cc7941