Increase minimum macOS version to 13.0

[mischreiber]

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

• Increasing minimum macOS version from 12.0 to 13.0.
• Removing version checks in code for macOS 12.0 and below.

Verification

Ran full automation in both light and dark mode, verifying behavior and appearance.

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