Implement configuration for keybindings

Keybinds go in a "keybinds" block and follow the format

<command> <modifiers> <keysym> <options>

But there's also a special "tag_bind" command that just takes modifiers
and one of set_output_tags, set_window_tags, toggle_output_tags, and
toggle_window_tags. It will automatically be used to loop through the
1-9 keys on tags 1<<0 to 1<<9, however, you can still implement those
commands individually if you want.

examples/config.kdl

@@ -1,10 +1,20 @@
 attach_mode top
-
-focus_follows_pointer true
-pointer_warp_on_focus_change true
-
+focus_follows_pointer #true
+pointer_warp_on_focus_change #true
 borders {
-	width 2
-	color_focused 0x89b4fa
-	color_unfocused 0x1e1e2e
+    width 2
+    color_focused "0x89b4fa"
+    color_unfocused "0x1e1e2e"
+}
+keybinds {
+    spawn mod4 t foot
+    focus_next mod4 j
+    focus_prev mod4 k
+    toggle_fullscreen mod4 f
+    close_window mod4+Shift q
+    // Generates keybinds for keys 1-9 → tags 1<<0 through 1<<9
+    tag_bind mod4 set_output_tags
+    tag_bind mod4+shift set_window_tags
+    tag_bind mod4+ctrl toggle_output_tags
+    tag_bind mod4+ctrl+shift toggle_window_tags
 }