Bug/Feature Request: NavigationView FooterMenu - No overflow handling for Top mode

[anawishnoff]

Describe the bug
With the addition of the FooterMenu from Issue #375 and PR #1997, the corner case of having an overflow of footer menu items in a top mode NavigationView was not handled. Currently, if you add more footer items than can fit within the viewport of the NavigationView in top mode, the items will render "off-screen" - they aren't visible and they aren't able to be scrolled to.

Steps to reproduce the bug

Steps to reproduce the behavior:

1. Set PaneDisplayMode = Top on a NavigationView
2. Add multiple items to FooterMenuItems until they can't all fit within the NavigationView
3. See that those overflowing items are inaccessible to the user.

Expected/Suggested behavior
There should either be a ScrollViewer that horizontally scrolls all of the overflow FooterMenuItems or there should be a flyout that holds the overflow items. Implementation/behavior of this feature is still up for discussion.

[ad1Dima]

Some screenshots for context

[github-actions]

This issue is stale because it has been open 180 days with no activity. Remove stale label or comment or this will be closed in 5 days.