fix(wm): don't attach to the desktop window thread

Noticed in the logs when looking at issue #2 that an "Access is denied.
(os error 5)" error was being reported when trying to attach to the
thread of the special Desktop Window, which only happens when switching
to a workspace which doesn't contain any windows. Calling
WindowsApi::set_foreground_window on the HWND directly seems to be the
better option here.

komorebi/src/window_manager.rs

@@ -89,7 +89,11 @@ impl WindowManager {
                     hwnd: WindowsApi::desktop_window()?,
                 };
 
-                desktop_window.focus()?;
+                // Calling this directly instead of the window.focus() wrapper because trying to
+                // attach to the thread of the desktop window always seems to result in "Access is
+                // denied (os error 5)"
+                WindowsApi::set_foreground_window(desktop_window.hwnd())
+                    .map_err(|error| eyre::anyhow!("{} {}:{}", error, file!(), line!()))?;
             }
         }