Implement-pr-45

[kingdomseed]

Implement I/O improvements from PR deansyd#45 (original repository):

• Add getContainerPath method to access the root iCloud container directory
• Modify download method to return a boolean success value
• Remove destinationFilePath parameter from download method
• Update documentation to reflect new API usage patterns
• Add examples for using the new container path access feature
• Update tests to match the new API signatures

These improvements enhance file operations by providing direct access to the
iCloud container and simplifying the download process, following Apple's
guidelines for iCloud integration.

Updated macOS platform channel implementation.