Implement global navigation shortcuts as per "global mode" table in M6 Keyboard navigation

Note:

• Shortcut help is covered by MGNLUI-4044

Implementation details

Implementing these single character global navigation shortcuts will require client-side changes, at minimum adapting the KeyActions vaadin add-on to prevent propagation of key events from input fields, or to have it pass the target of the key event, so key events targeted to input fields can be filtered out on server side.

Šimon: note to self - Sasha had an app switcher client side project which could serve as a starting point for the client side necessary changes. Check it out when starting work on this ticket https://git.magnolia-cms.com/projects/MODULES/repos/appswitcher/browse