Changes to Get a single OpportunityStatusChange activity

added the media type application/json for the response with the status 400

added the media type application/json for the response with the status 401

added the media type application/json for the response with the status 404

added the non-success response with the status 403

added the non-success response with the status 429

added the optional property created_by_agent_id to the response with the 200 status

added the optional property updated_by_agent_id to the response with the 200 status

added the new optional query request parameter _fields