Topcoder - Returns Winners Info For Challenge Listing Endpoint

For challenge listing endpoint (GET /challenges) in challenge service, we'd like to return winners info for the listed challenges when the information is available.

1. Add a winners field for holding the winners info (array type), each element should contain the following properties for each winner.

- type: {checkpoint|final}
- placement
- user_id
- handle
- photo URL

2. For each api call, it should use one query to retrieve all the info for winners, the query is mainly against the following tables
- upload
- submission
- prize
- user

please check https://github.com/topcoder-platform/tc-database-scripts/blob/dev/tcs_catalog/query_tool/query_studio_contest_results.txt for better understanding, and take the reference to create the query to retrieve all the winner info

3. Create/Update Postman Script for Easily of testing updated APIs

4. swagger.yaml should be properly updated for the changes.

About Local Setup

- Please check https://github.com/appirio-tech/tc-common-tutorials/tree/master/docker/direct-app about how to build, deploy and run direct-app locally. 
- Be sure to start the elasticsearch feeder service, otherwise, the challenge service will not work
- Please use Topcoder Direct to setup the test challenge data.
- Please check ap-challenge-microservice.zip/docs/Deployment Guide.docx about how to run the service and test with the API.

Final Submission Guidelines

- Code changes for the requirements above
- Postman scripts for easily of testing
- Updated swagger.yaml file
- Verification Steps