docs: enhance score set create/patch endpoints with detailed OpenAPI schema for file uploads

[bencap]

This pull request enhances the OpenAPI documentation for the score set upload and patch endpoints by explicitly defining the multipart form data schema for file uploads and associated metadata. These changes improve API usability and clarity for clients interacting with these endpoints.

OpenAPI schema improvements for file upload endpoints:

• Added detailed openapi_extra definitions to the create_score_set endpoint, specifying the multipart form data schema for required and optional files (scores_file, counts_file, score_columns_metadata, count_columns_metadata), including descriptions and data types.
• Enhanced the upload_score_set_variant_data endpoint with an explicit multipart form schema in openapi_extra, including all updateable score set properties and optional file uploads, improving the OpenAPI documentation for clients.