Add displayselect from Luke Smith's dotfiles

nix/pkgs/displayselect/remove-setbg.patch

@@ -0,0 +1,12 @@
+diff --git a/.local/bin/displayselect b/.local/bin/displayselect
+index 51dd468..f69f154 100755
+--- a/.local/bin/displayselect
++++ b/.local/bin/displayselect
+@@ -57,7 +57,6 @@ onescreen() { # If only one output available or chosen.
+ 	}
+ 
+ postrun() { # Stuff to run to clean up.
+-	setbg		# Fix background if screen size/arangement has changed.
+ 	{ killall dunst ; setsid -f dunst ;} >/dev/null 2>&1 # Restart dunst to ensure proper location on screen
+ 	}
+