Unify UI approach for in-page menus (side menus vs top menus)

Refactor side menus and top menus to simplify and unify the user interface and user experience. This change allows page flow to work more appropriately at different widths, reduces clutter, and provides consistency. The change allows forms and tables that currently fall to the left of the side menus to regain full browser width.

If the top menus grow too long, or the browser width pulled narrow (or on moblie), the new flow will allow the top menus to drop below the page title.

On the very few pages where very long side menus may exist (e.g. the person canvas), the side menu may be retained. At some point we may consider using a hamburger menu in these cases, or simply letting the menus wrap under the page title.