Add disabled trait to tab bar item view

[joannaquu]

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

When TabBarItemView is disabled, VoiceOver/the accessibility inspector do not accurately report that it is disabled. Update it so that we add/remove the notEnabled accessibility trait when isEnabled changes.

Binary change

I no longer trust this at all. I triple checked this and somehow adding traits decreases our binary size??? I also confirmed that I wasn't doing the before/after comparison in the wrong direction.

Total increase: 48 bytes
Total decrease: -368 bytes

File	Before	After	Delta
Total	32,172,808 bytes	32,172,488 bytes	🎉 -320 bytes

Full breakdown

File	Before	After	Delta
__.SYMDEF	4,887,416 bytes	4,887,464 bytes	⚠️ 48 bytes
TabBarItemView.o	236,952 bytes	236,584 bytes	🎉 -368 bytes

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