[Feature] Improve keyboard navigation

[miroiu]

Describe the solution you'd like

• Automatically bring item containers into view when navigating to them via keyboard if they are not already in view
• Enable directional navigation for item containers within the editor

Describe alternatives you've considered
Using KeyboardNavigation attached properties. While this approach works in most cases, it becomes limiting when access to the internal control XAML is required, especially if overriding styles is not desirable.