Add required boolean option to Autotoc tabs

[davilima6]

The goal is feature parity with Plone 4.x, which by default displays a required icon in tabs that contain required fields.

It could be done by copying existing classes from level elements to tabs (.autotoc-nav a) -- and then updating the existing CSS selector, since pre-p.a.widgets one relies on an extra span.

However if we do it so generically, instead of required I wonder if we shouldn't we call this option classLevelCopyOrigin, copyOriginalLevelsClasses or something clearer?

[gurramkarthiknetha]

This issue I want to take this up this issue if you are not solving...