[Fluent 2 iOS] Created new alias tokens for shared colors

[laminesm]

Platforms Impacted

• [x] iOS
• [ ] macOS

Description of changes

New alias tokens were added for shared colors. Just like the rest of the color tokens, they were added to the ColorsTokens enum.

Verification

• Ran the demo app to ensure nothing was broken
• Tested a random selection of tokens on PopupMenu

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)