New Asset Endpoints: List and Delete

We’ve expanded the Asset API with new endpoints for easier asset management:

• Endpoint: /v1/asset/list — List assets with pagination and filters for file_type and folder_id.
  Reference: https://docs.heygen.com/reference/list-assets
• Endpoint: /v1/asset/<asset_id>/delete — Delete a single asset by its ID.
  Reference: https://docs.heygen.com/reference/delete-asset