Add changeWorkspace method

[JoshKiff]

Summary

• Adds changeWorkspace() method to allow switching between Intercom workspaces
• Android: Uses native changeWorkspace API (SDK 16.1.0+)
• iOS: Implements via logout and re-initialization pattern
• Web: Implements via shutdown and boot with new app ID
• Includes platform-specific API key parameters (androidApiKey, iosApiKey)

Implementation Details

• Platform interface updated with new method signature
• Method channel implementation added for iOS/Android
• Web implementation using Intercom JS SDK
• Proper error handling for missing required parameters
• Code formatting improvements across multiple files

Test Plan

• Test workspace change on Android with valid credentials
• Test workspace change on iOS with valid credentials
• Test workspace change on Web with valid app ID
• Verify user is logged out after workspace change
• Test that login works correctly after workspace change
• Test error handling with missing parameters

🤖 Generated with Claude Code

[deepak786]

Thank you for the PR.
To review it properly, please remove the unwanted changes.