Improve handling of drawer items that trigger navigation.

Today it is possible to add drawer items that trigger navigation using nuxeo-menu-icon, by using either the route or the link properties. However, these will still trigger the drawer to open, which will result in a blank drawer page. We need to to do some research to find a way to prevent this from happening.

A possible (and rather trivial) solution would be to add an on-tap listener on the anchor element inside the nuxeo-menu-icon, and make this listener stop propagation if either route or link are defined.

We should use this ticket to fix the current behavior of the link property, which does not take the base path into account.