Add device-specific tunings for external touchpads

These are copied over from the ChromiumOS tunings [0], translated from
their Xorg-style configuration syntax into IDC syntax. In a couple of
places I've included context for property changes from the commit
history of the source file.

[0]: https://crsrc.org/o/src/platform/xorg-conf/40-touchpad-cmt.conf;drc=e51f71c8cae6da8ce073ed10b03dedfbee476b9e

Bug: 271251605
Test: connect Apple Magic Trackpad 2, check properties are set correctly
      in dumpsys input
Change-Id: I590f3b40440c13c8a0b50d699fabd27a118d9a10