[video_player] Adds audio track metadata fetching and audio track selection feature (#9925)

## Description

This PR adds comprehensive audio track retrieval and selection support to the video_player package, enabling developers to access detailed information about available audio tracks and switch between them during playback.

Breakout PRs: 
1. Platform interface : #10171 
2. Andrioid : #10312 
3. ios : #10313 

### Changes Made

#### Core Features
- **Added `VideoAudioTrack` model** with comprehensive metadata fields: `id`, `label`, `language`, `isSelected`, `bitrate`, `sampleRate`, `channelCount`, `codec`
- **Added [getAudioTracks()]() method** to retrieve all available audio tracks with real metadata
- **Added [selectAudioTrack()]() method** to switch between audio tracks during playback
- **Updated `VideoPlayerController`** to expose audio track functionality

#### Platform Implementations
- **Android**: 
  - Real metadata extraction using ExoPlayer's `getCurrentTracks()` API
  - Robust track selection using `TrackSelectionOverride` with proper error handling
  - Support for multiple audio formats (AAC, AC3, EAC3, MP3, etc.)
- **iOS**: 
  - Metadata extraction from AVFoundation using `AVAssetTrack` for regular videos
  - HLS stream support using `AVMediaSelectionGroup` for adaptive streams
  - Proper track selection for both asset tracks and media selection options

#### Technical Infrastructure
- **Updated Pigeon interfaces** for both Android and iOS with new data structures:
  - `AudioTrackMessage`, `ExoPlayerAudioTrackData`, `AssetAudioTrackData`, `MediaSelectionAudioTrackData`, `NativeAudioTrackData`
- **Enhanced platform interface** with new methods and data classes
- **Has native unit tests** for both Android and iOS platforms
- **Created demo screen** showcasing audio track functionality with interactive UI

### Demo Features
- Interactive video player with audio track selection
- Real-time metadata display (bitrate, sample rate, channels, codec)
- Support for multiple video sources including HLS streams
- Visual indicators for currently selected tracks

## Related Issues
Fixes flutter/flutter#59437

### Testing
- Added native unit tests for both Android and iOS
- Tested with various video formats and HLS streams
- Verified backward compatibility with existing functionality
- Demo screen widget for manual testing and validation

### Breaking Changes
None - all changes are additive and backward compatible.

## Pre-Review Checklist

Author: nateshmbhat

packages/video_player/video_player/CHANGELOG.md

@@ -1,6 +1,7 @@
-## NEXT
+## 2.11.0
 
-* Updates minimum supported SDK version to Flutter 3.35/Dart 3.9.
+* Adds `getAudioTracks()` and `selectAudioTrack()` methods to retrieve and select available audio tracks.
+* Updates minimum supported SDK version to Flutter 3.38/Dart 3.10.
 * Updates README to reflect currently supported OS versions for the latest
   versions of the endorsed platform implementations.
   * Applications built with older versions of Flutter will continue to

packages/video_player/video_player/example/ios/Runner.xcodeproj/project.pbxproj

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