Implement TCO23 leaderboards in Contentful

[kkartunov]

New theme for TCO Leaderboards is in scope.

• https://topcoder.atlassian.net/browse/PROD-2201
• Design: https://www.figma.com/file/00KWINUF6mPw9wuSELyGVs/TCO23?node-id=14%3A2326

[sandhiyakavi]

Verified in Staging Env.

Screenshot: https://topcoder.atlassian.net/browse/PROD-2201?focusedCommentId=22846