app/internal/wm: rename confusing app/internal/window

Package wm (for "window manager") is a better fit for the package, and
distinguishes it from the low-level package windows for the Windows API.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/internal/wm/framework_ios.h

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+#include <UIKit/UIKit.h>
+
+@interface GioViewController : UIViewController
+@end