Ensure TableViewHeaderFooterView has a themed default text color and font style

[nodes11]

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

Issue: Attributed strings in the TableViewHeaderFooterView were showing as black if a foreground color attribute was not provided.

Root Cause: The attributed text color will default to the textColor of the UITextView. According to the Apple documentation, the default text color for a UITextView is black, explaining why we were seeing the text show as black in both light and dark modes

Fix: Check if an attributed foreground color is provided with string. If not, apply the fluent theme text color. Also do the same thing for font.

Binary change

Total increase: 19,560 bytes
Total decrease: 0 bytes

File	Before	After	Delta
Total	30,900,560 bytes	30,920,120 bytes	⚠️ 19,560 bytes

Full breakdown

File	Before	After	Delta
TableViewHeaderFooterView.o	282,296 bytes	297,712 bytes	⚠️ 15,416 bytes
__.SYMDEF	4,744,576 bytes	4,746,832 bytes	⚠️ 2,256 bytes
FocusRingView.o	834,848 bytes	836,576 bytes	⚠️ 1,728 bytes
PopupMenuSectionHeaderView.o	24,496 bytes	24,656 bytes	⚠️ 160 bytes

Verification

• In the demo controller, I validated that an attributed string with both foreground color and font attributes uses the attributes.
• In the demo controller, I validated that an attributed string without a foreground color and font attributes uses the fluent theme colors.
• Validated that the change fixes our internal use case.

Visual Verification

Before change, without attributes applied to string:

After change, without attributes applied to string:

After change, with attributes applied to string:

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

[joannaquu]

can you run the binary size change