Allow @objc accessibility for colors in GlobalTokens

[mischreiber]

Platforms Impacted

• iOS
• macOS

Description of changes

Making GlobalTokens be accessible from Objective-C.

Currently focused on colors

Verification

Colors still load as expected in both Swift and Objective-C.

Swift	Objective-C

Binary size impact on test app:

Before	After	Delta
31,715 kb	31,784 kb	+ 69 kB

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

[edjamesmsft]

Consider moving to colors branch to keep 0.9 slim, binary-wise?

[mischreiber]

Consider moving to colors branch to keep 0.9 slim, binary-wise?

Think I'm gonna take it to main for now and eat the cost -- I want to minimize the number of unique diffs in fluent2-colors wherever possible.