FeatureFormView - Use List

[dfeinzimer]

Builds on @zkline101's work in #1034 to enhance FeatureFormView by converting the internal VStack to a List.

Since #1034, FeatureFormView has grown in complexity to support UtilityAssociationsFormElements. As part of that work, FeatureFormGroupedContentView was needed to mimic the appearance of a section in a list. FeatureFormView was also refactored to wrap a new internal EmbeddedFeatureFormView with a NavigationStack. With more form elements in the pipeline, now is a good time to revisit adopting platform provided types like List to streamline future enhancement work.

Issues

• A GroupFormElement will revert to its initial expanded/collapsed state when it's scrolled out-of and back into view.
• UI tests require manual scrolling to targeted form elements due to the lazy nature of a list.
  • This scrolling is unstable on Mac Catalyst (FB19836397)
• Section headers are cut off by the navigation bar when form elements are focused & scrolled-to. (FB19740517)

Considerations

• We lose the ability to remove the border around read-only elements. We have to indicate read-only via another manner.
• Semantically, Form makes more sense than List, however I've found no practical visual difference between the two. List also has a convenient init(_:id:editActions:rowContent:) that lets us avoid an inner ForEach. Form does not provide the same.