Add support for new Translation Import API endpoints

The Crowdin API has been extended with new Translation Import endpoints that provide a more efficient way to import translations. Additionally, the legacy translation upload method has been deprecated.

The Crowdin API client libraries need to be updated to include these new endpoints and mark the deprecated method accordingly.

**New Endpoints:**
- [Import Translations](https://support.crowdin.com/developer/api/v2/#tag/Translations/operation/api.projects.translations.imports) - Upload translation files for import
- [Check Translation Import Status](https://support.crowdin.com/developer/api/v2/#tag/Translations/operation/api.projects.translations.imports.get) - Get import operation status
- [Download Translation Import Report](https://support.crowdin.com/developer/api/v2/#tag/Translations/operation/api.projects.translations.imports.report.get) - Download detailed import report

**Deprecated:**
- [Upload Translations (Legacy)](https://support.crowdin.com/developer/api/v2/#tag/Translations/operation/api.projects.translations.postOnLanguage) - This method is deprecated in favor of the new Import Translations endpoint

**References:**
- [Import Translations](https://support.crowdin.com/developer/api/v2/#tag/Translations/operation/api.projects.translations.imports)
- [Check Translation Import Status](https://support.crowdin.com/developer/api/v2/#tag/Translations/operation/api.projects.translations.imports.get)
- [Download Translation Import Report](https://support.crowdin.com/developer/api/v2/#tag/Translations/operation/api.projects.translations.imports.report.get)
- [Upload Translations (Legacy - Deprecated)](https://support.crowdin.com/developer/api/v2/#tag/Translations/operation/api.projects.translations.postOnLanguage)

Start by reviewing the existing translation-related methods in the Go client and the four referenced Crowdin API operations. Confirm the request and response patterns for importing translations, checking status, and downloading the report. Done means the three new endpoints are represented and the legacy upload method is marked deprecated.

Written by the indexing model from the issue text.