'Expand all' action for expandable nav

[maryshak1996]

On console.redhat.com, we use the expandable navigation component generously, with some applications (Red Hat Insights to be exact) using the expandable nav down to third-level navigation. In this particular case, if a user wanted to skim the navigation items, they would need to click open 13 expansion carets to see all 32 navigable pages.

I've attached a screenshot of the existing left navigation with a possible solution for an expand-all feature that closely mimics the expand-all in expandable tables