Call wlr_idle_notify_activity when executing a keybinding
wlr_idle_notify_activity
is only ever called in seat.c
and the activity isn't registered when a keybinding is pressed. Currently this gets kinda workaround due to #186, but fixing that will make keybindings unnoticed from idle timer perspective. It seems to me that all keybindings, possibly except the power button press (which eventually should get moved into phosh anyway), should generate such notification.