Support hiding or adjusting pages based on connected input devices (ex: multitouch trackpads, touchscreens, keyboards)

A key part of the onboarding for GNOME 40 (Teams/Design/os-mockups#79 (closed)) is teaching users about the new three-finger touchpad gestures.

I believe that most computers either always have a touchpad (because they are a laptop, or less likely because they are a desktop with a touchpad attached) or will never have a touchpad (a desktop which is sometimes, but not always, attached to a touchpad?). So if the tour is run on a system where it is not possible to perform these gestures, those pages should either be hidden, or adjusted to refer to keyboard shortcuts to trigger the same actions.

gnome-control-center has some rather simple code using API from gnome-setting-daemon to check whether a touchpad is present:

https://gitlab.gnome.org/GNOME/gnome-control-center/blob/44b7e37fb40e3172d0f25e14a932ea70bd2a0af9/panels/common/gsd-input-helper.c#L34-52

There are at least 2 other cases to consider:

• My Dell XPS 13 9343 from 2015 has a touchpad that does not support three-finger gestures. (It supports 3- and 4-finger taps, but only 1- or 2-finger gestures, based on someone helping me to understand evdev properties.)
• I believe that 3-finger gestures are not supported on X11.

In both of those cases, I think the non-gesture case should be enabled.