feat(cli): add focused-container-kind state query

This commit adds a new StateQuery variant, FocusedContainerKind, which
will will return None if there is not focused container on the current
workspace (ie. it is empty), Single if the focused container contains a
single window, or Stack if the focused container contains more than one
window.

docs/cli/toggle-shortcuts.md

@@ -0,0 +1,12 @@
+# toggle-shortcuts
+
+```
+Toggle the komorebi-shortcuts helper
+
+Usage: komorebic.exe toggle-shortcuts
+
+Options:
+  -h, --help
+          Print help
+
+```