[web/navigation] use add_onload instead of inline javascript href
This way our javascript code isn't thrown out by the html cleaner e.g. when
using the rql rest directive and a table view.
To make things simpler, we now always use ajax URLs for navigation,
even when we would previously have used regular links.
Closes #3501626
missing-dep-for-interpreter make => make | build-essential | dpkg-dev (usr/share/pyshared/cubicweb/skeleton/debian/rules.tmpl)