For some reason, hidpp20 device names were badly set (e.g.
'Wireless Mouse MWireless' instead of 'Wireless Mouse MX Master').
Adding a 100ms delay to addDevice seems to have fixed it.
Multiple things have been done in this commit; the base of the new
backend has effectively been created. This branch currently has many
vital parts commented out. Therefore, this branch is currently only
intended for debugging.