Add support for new File References API

[andrii-bodnar]

The Crowdin API has been extended with new endpoints, allowing you to manage asset file references in your Source Files workflow.

The Crowdin API client libraries need to be updated to include these new endpoints.

References:

• List File References
• Get File Reference
• Add File Reference
• Delete File Reference

[GauravJangra9988]

@andrii-bodnar I would like to work on this, please assign me.