Added a cli method to check the visibility of a window. (#301)

globals/utilities.ts

@@ -0,0 +1,8 @@
+globalThis.isWindowVisible = (windowName: string): boolean => {
+    const appWindow = App.getWindow(windowName);
+
+    if (appWindow === undefined) {
+        return false;
+    }
+    return appWindow.visible;
+};