Remove/update menuitems and menu

remove menuitems as they are not part of the HTML living standard:

menu is part of the HTML living standard, so this should stay in AAM, but it does not accept a type attribute.

Initial work done to remove menuitem types from the spec. Still need to review menu

Note: <menu> should map to role="list" per the Living Standard definition.

Per the note in the menu definition:

The menu element is simply a semantic alternative to ul to express an unordered list of commands (a "toolbar").

Navigation Menu