[iOS] Updating Version.plist keys to match other plists

[mischreiber]

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

The FluentUI_iOS library was using different keys to store its version info compared to every other plist in the repo. Let's just consolidate onto the same standard CFBundleVersion/CFBundleShortVersionString naming pattern, to make version increases easier.

Binary change

Before	After	Delta
16,525,060	16,525,126	62 bytes

Verification

Ran the BumpVersion.swift script to confirm that the new plist is correctly updated.

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