FloorFilter: Convert to NavigationStack

[dfeinzimer]

As of 200.8, there is a precedent for components to use NavigationStacks to provide internal navigation. Floor Filter would probably be another component that could benefit from using a NavigationStack internally to navigate back and forth between site and facility selections.

• Floor Filter: All Sites button is cut off on the bottom on Mac Catalyst #1247 could be resolved by using the bottom toolbar.
• An alignment issue in the navigation bar found by @PeggyDu09 could also be resolved:

  • the navigation button and the close button seem slightly misaligned.

    • 

One thing we need to consider is that the component is currently two visually separate pieces of UI. The skinnier level selector and the wider site and facility selector. The level selector is designed to be persistently visible, while the site and facility selector is designed to be toggled between hidden and visible. We'd likely need to change and deliver these as two separate views and provide a model type that binds them together.