Accent translation files download support

[like-engels]

Description:

Implement Accent Translation file download support, allowing users to fetch translation files from an Accent endpoint with the whisper accent fetch command.

Changes required:

• Update the whisper.toml configuration file to include:
  • Accent endpoint URL
  • Authorization token
• Create a new API endpoint to handle translation file downloads
• Implement a mechanism to validate the provided endpoint and token

Scope of changes:

• Configuration file updates
• API endpoint addition
• Validation mechanism implementation

Acceptance Criteria:

• Users can successfully download translation files from the specified Accent endpoint
• The endpoint and token are validated before file download
• Error handling is implemented for invalid endpoint or token

Test Plans:

• Create a test case that provides a valid endpoint and token and verifies the successful file download
• Create a test case that provides an invalid endpoint or token and verifies the error handling
• Create a test case that verifies the validation mechanism