i3: pause/upause dunst around i3lock
i3: pause/upause dunst around i3lock

This prevents dunst from showing notifications when the screen is locked
which causes flickering and exposes the desktop. Dunst keeps notifications
in a queue and displays them when it's unpaused. RTFM `man 1 dunst`.

lathan/dotfiles,lathan/dotfiles,lathan/dotfiles,lathan/dotfiles,lathan/dotfiles