polybar: Add labels for bspwm status

Now that I understand the difference between the monocle desktop
layout and the fullscreen state of a node, it became clear that I
would probably use both.

Since I use the single_monocle config option, desktops with the
tiled layout may contain a monocle node, so I needed a way to tell
which layout a desktop was running.

I initially thought about using sxhkd to send a notification with
the layout portion of bspc query -T -d, however polybar supports
showing the layout natively, so I don't need to use a keybind.

The layout portion of the polybar config may not be needed if, for
example, you decide to disable single_monocle and there is no ambiguity
between fullscreen nodes and monocle desktops.

.config/polybar/config

@@ -77,6 +77,22 @@ wm-restack = bspwm
 type = internal/bspwm
 pin-workspaces = true
 
+format                      = <label-mode> <label-state>
+label-monocle               =  monocle mode
+label-locked                =  Locked
+label-private               =  Private
+label-sticky                =  Sticky
+
+label-monocle-padding       = 1
+label-locked-padding        = 1
+label-private-padding       = 1
+label-sticky-padding        = 1
+
+label-monocle-foreground    = ${color.yellow}
+label-locked-foreground     = ${color.background-alt}
+label-private-foreground    = ${color.background-alt}
+label-sticky-foreground     = ${color.background-alt}
+
 label-focused-foreground    = ${color.text}
 label-urgent-foreground     = ${color.yellow}
 label-occupied-foreground   = ${color.background-alt}