Navigation Component: Store the Navigation Tree in the Context

[Copons]

Explore if we should keep an abstraction of the navigation tree (derived by the Navigation children) in the NavigationContext, in order to facilitate some automations that would otherwise require manually traversing the Navigation children.

Examples:

• Automatize the back button label for nested menus. (Navigation Component: Improve the Back Navigation #25247)
• Automatically add an ul inside NavigationMenu if not provided by the consumer. (Navigation Component: Add ul Automatically Where Needed #25248)
• Check that setActiveItem and setActiveMenu are targeting existing targets. (Navigation Component: Ensure That setActiveItem and setActiveMenu Targets Exist #25249)

[david-szabo97]

Taking this!