support nested page object models

[michaelgoeke]

e.g. given class home_page and class menu_header would like to have property home_page.menu_header reference nested page object model.
Nested page object model should include outer scope selector (prefix selector) from the point of view of the hosting page.
e.g.

import { Page } from "@playwright/test";
import { menu_header } from "./menu_header";

export class home_page {
    private static menu_header_selector = `[data-testid="menuHeader"]`;
    static menu_header = menu_header;

    //additional properties...
}