sxhkd: Use rofi launch script

This gives the task of setting environment variables to rofi's
launch.sh, instead of trying to do it in sxhkdrc.

Another benefit is that rofi can be launched properly from anywhere,
regardless of whether or not sxhkd is being used.

sxhkd/.config/sxhkd/sxhkdrc

@@ -28,8 +28,11 @@ alt + m
   wal -o ~/.config/wal/done.sh -i ~/Pictures/Wallpapers
 
 # Show rofi drun / window / calc
-alt + {z,space,backslash}
-  env XDG_CURRENT_DESKTOP="KDE" rofi -show {drun,window,calc -modi calc -no-show-match -no-sort}
+alt + z
+  ~/.config/rofi/launch.sh
+
+alt + {space,backslash}
+  rofi -show {window,calc -modi calc -no-show-match -no-sort}
 
 # Show rofi-pass
 alt + slash