[menu-bar] Add API for closing the overlay(s)

[pekam]

Use case: In the menu bar's overlay, we have a component which is not a vaadin-context-menu-item (added with the Java API, but can as well be done with the web component's item.component API). When clicking this component, we'd like the overlay to close.

Currently, the overlay closes only when selecting a vaadin-context-menu-item, and there's no public API to close the menu's manually eg. on click event.

A simple close function would be useful (with Java API as well).

Workaround: menuBar._subMenu.close()

[mvysny]

Definitely a good addition, especially when I implement PopupButton by using MenuBar.

[sissbruecker]

Has been resolved with #7102

[mvysny]

Will this be backported to Vaadin 23 please?