Adding a convenience init for FluentListSection

[mischreiber]

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

Adding a convenience initializer for FluentListSection where SectionHeaderContent == Text, SectionFooterContent == EmptyView.

// MARK: - Before

FluentListSection {
    // ...
} header {
    Text("Hello!")
}

// MARK: - After

FluentListSection("Hello!") {
    // ...
}

Binary change

Total increase: 6,576 bytes
Total decrease: -8 bytes

File	Before	After	Delta
Total	31,212,536 bytes	31,219,104 bytes	⚠️ 6,568 bytes

Full breakdown

File	Before	After	Delta
FluentListSection.o	38,992 bytes	44,392 bytes	⚠️ 5,400 bytes
__.SYMDEF	4,865,344 bytes	4,866,520 bytes	⚠️ 1,176 bytes
FluentListSectionHeader.o	47,632 bytes	47,624 bytes	🎉 -8 bytes

Verification

No changes to FluentListSection uses.

Visual Verification

ListItem	ListActionItem

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