feat-req(menu): Specs for desktop

(As it seems there's no issue yet, I'll create one for tracking purposes.)

Bug, feature request, or proposal:

feature request

What is the current behavior?

The menu is only available with specs for mobile.

What is the expected behavior?

There should be something like a desktop mode for the menu, as the MD Guidelines describes it in the specs:

Default desktop menu
Menu item height: 32px
Menu item text left padding: 24px
Top padding: 8px
Bottom padding: 8px
Typography: 15px

Dense desktop menus
Menu item height: 24px
Menu item text left padding: 24px
Top padding: 4px
Bottom padding: 4px
Typography: 13px

Default Cascading menu
Cascading menu top padding: 16px
Cascading menu left padding: 24px
Cascading menu item height: 32px
Menu item icon right padding: 32px
Menu sub-item left padding: 64px
Typography: 15px
Dense Cascading menus can use 13px typography

I find it a little bit strange that the specifications are so different when the menu has cascading elements.