sway: Add alt tab support

This is similar to bspwm, except new workspaces aren't automatically
created and empty workspaces are skipped.

Although creating a script to handle this should be possible, sway
doesn't offer any real benefits to me since bspwm does everything that
sway can do with the addition of input method, image preview, and other
features being better supported on xorg.

To reiterate, I like the idea behind sway, however I am more fluent with
bspwm and xorg and prefer how windows are managed in bspwm. For software
that only works on wayland, sway is a lightweight alternative to
committing to a full-featured desktop environment like GNOME.

sway/.config/sway/config

@@ -89,6 +89,10 @@ input "1:1:AT_Translated_Set_2_keyboard" {
     bindsym $mod+Shift+0 move container to workspace number 10
     # Note: workspaces can have any name you want, not just numbers.
     # We just use 1-10 as the default.
+
+    # Jump to previous/next workspace
+    bindsym $alt+Tab workspace next
+    bindsym $alt+Shift+Tab workspace prev
 #
 # Layout stuff:
 #