Use keyboard+touchpad as desktop-first criteria

This CL changes criteria for the desktop first switch to use keyboard
and touchpad [dis]connection.
Tablet signal or mouse connection no longer fits the latest spec.

Flag: com.android.window.flags.form_factor_based_desktop_first_switch
Bug: 400645703
Test: DesktopDisplayModeControllerTest
Change-Id: I6c74dca8a485f7f17ba1d623faf5c23a92876c98