Initial visionOS integration

[mischreiber]

Platforms Impacted

• iOS
• macOS

Description of changes

This PR represents a very WIP implementation of the FluentUI library and demo app for visionOS. Most components are still pretty broken and not yet supported, but a variety of core scenarios are now viable for additional exploration.

This is not full visionOS support!

That said, this at least unblocks any downstream apps that want to build against visionOS and utilize some aspects of the FluentUI library.

Some important caveats:

• CocoaPods is not yet supported. Only SPM and direct library integration are currently available. We'll continue to monitor visionOS support in CocoaPods and evaluate accordingly.
• Some alias tokens have been updated with hardcoded values. This will be eventually removed and migrated to a proper per-platform override system.
• As mentioned above, many components are either unsupported or have not been throughly verified on visionOS. Please treat this as an experimental WIP.

Binary change

Note: the script for processing binary changes seems to be having problems with my build. While I investigate, here's the quick breakdown:

File	Before	After	Delta
Total	31,037,192 bytes	31,114,936 bytes	⚠️ 77,744 bytes

Verification

iOS app builds and runs as expected. visionOS app detailed below:

Visual Verification

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

[huwilkes]

Should this go into a separate visionOS branch for a lot of the same reasons we decided to not let the Catalyst changes into main?

Edit:

• Fix no such module 'FluentUI_ios' on MacCatalyst #1878

for context

[mischreiber]

Should this go into a separate visionOS branch for a lot of the same reasons we decided to not let the Catalyst changes into main?

Edit:

• Fix no such module 'FluentUI_ios' on MacCatalyst #1878

for context

Added clearer indications in the demo as to which controls are enabled. I'll also be working to fix accessibility for a handful of cases where the controls are usable but the demo itself is not to our standards.