[List Item] Add animation when adding or removing subtitle/footer

[alexanderboswell]

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

For some scenarios, we will be asynchronously be adding or removing the subtitle for a list item. We dont take advantage of any animations that SwiftUI provides to have a polished transition for the UI.

The changes make it so we can animate based on if the layoutType changes. Also simplify all the scenarios handled by a change in layoutType by defining a few more view builders.

Binary change

All internal API changes, not calculated.

Verification

Visual Verification

Before	After

Pull request checklist

This PR has considered:

• Light and Dark appearances
• iOS supported versions (all major versions greater than or equal current target deployment version)
• VoiceOver and Keyboard Accessibility
• Internationalization and Right to Left layouts
• Different resolutions (1x, 2x, 3x)
• Size classes and window sizes (iPhone vs iPad, notched devices, multitasking, different window sizes, etc)
• iPad Pointer interaction
• SwiftUI consumption (validation or new demo scenarios needed)
• Objective-C exposure (provide it only if needed)

Microsoft Reviewers: Open in CodeFlow