Dropdown backround should not be scrollable on mobile

[mlmoravek]

Overview of the problem

Oruga version: [0.5.10]

The background of a dropdown in mobile mode is still scrollable.

Description

Steps to reproduce

See dropdown component on oruga documentation.

Expected behavior

I would expect a similar behavior like the modal component where i can define a scrollClipClass or a noScrollClass property which is added to the body when the modal opens.

Actual behavior

Wenn open a dropdown on mobile with mobileModal = true the background of the modal is still scrollable and it is not possible to add a class to the body or html element when the dropdown-modal is open.