[Templates] Ability to add classes to root element in header, footer, and modal

[jonte98]

When creating footers, modals, headers in templates etc… we have to add a section inside to control things like the entire background color.

The improvement is to eliminate the need of an extra div by being able to apply classes right to the element, or modal.

A small but great improvement.

[sm_websites]

At the moment, I want to add a class to a header template, but adding it to the Page Settings but it is not showing on the frontend.