Navigation: React support to enable docked nav variant

[andrew-ronaldson]

Follow up to:
Design - patternfly/patternfly-design#1243
Core - patternfly/patternfly#7183

The goal is to add support for a small docked version of our navigation with an icon view. This is a variant of the navigation component not a replacement.

Also related to patternfly/patternfly-design#1350
A flyout menu (drawer) option would be beneficial if there the docked nav item has children.