[macOS] Multiline Pill Picker

[mischreiber]

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

Created a new component, MultilinePillPicker, for macOS. Built in SwiftUI and wrapped (via [MSF]MultilinePillPickerView) for AppKit. Supports two rows of controls, with optional actions on selection.

Binary change

n/a - no measurement system for macOS as of yet.

Verification

Verified light and dark modes, enabled and disabled modes. See video and screenshots below.

Visual Verification

MultilinePillPickerRecording.mp4

Enabled	Disabled

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