This commit adds support for laptop lid and tablet
mode switches as provided by evdev/libinput and
handled by wlroots.
Adds a new bindswitch command with syntax:
bindswitch <switch>:<state> <command>
Where <switch> is one of:
tablet for WLR_SWITCH_TYPE_TABLET_MODE
lid for WLR_SWITCH_TYPE_LID
<state> is one of:
on for WLR_SWITCH_STATE_ON
off for WLR_SWITCH_STATE_OFF
toggle for WLR_SWITCH_STATE_TOGGLE
(Note that WLR_SWITCH_STATE_TOGGLE doesn't map to
libinput and will trigger at both on and off events)
