feat: createWindow API should allow window creation from URL

Right now, it only supports creating a window to execute a Kui command line.

This PR also updates the `createWindow` API so that it returns a `Promise` that resolves when the window is closed.

Author: starpit

packages/core/src/index.ts

@@ -286,4 +286,15 @@ export {
 
 export * from './api/window-events'
 
-export type CreateWindowFunction = (argv: string[], prefs?: import('./models/SubwindowPrefs').default) => void
+/**
+ * Open a new Kui window.
+ *
+ * @param argv If given a string, it will be treated as a URL to be
+ * displayed in the new Kui window. Otherwise, it will be treated as a
+ * command line to be executed in the new window.
+ *
+ * @param prefs? Options for the new window, such as desired width and height.
+ *
+ * @return a `Promise` that will resolve when the window closes
+ */
+export type CreateWindowFunction = (argv: string | string[], prefs?: import('./models/SubwindowPrefs').default) => void