feat(cli): add visible-windows cmd

This commit adds a new komorebic command, "visible-windows", to make
tracking down ghost windows easier. The returned JSON structure will try
to use the device id to identify a monitor if it is available, or fall
back to the monitor index. Thanks to raggi on Discord for suggesting
this command!

komorebi-core/src/lib.rs

@@ -147,6 +147,7 @@ pub enum SocketMessage {
     IdentifyLayeredApplication(ApplicationIdentifier, String),
     IdentifyBorderOverflowApplication(ApplicationIdentifier, String),
     State,
+    VisibleWindows,
     Query(StateQuery),
     FocusFollowsMouse(FocusFollowsMouseImplementation, bool),
     ToggleFocusFollowsMouse(FocusFollowsMouseImplementation),