Vix central service with single day and n day contango alert calculation

Features

• Update vix central service to calculate single day and n days contango alert

What's Changed

• Rename VIX central to third party VIX central by @hanchiang in #1
• Add VIX central service to get most recent values by @hanchiang in #2
• Update vix_central_service response format. by @hanchiang in #3

New Contributors

• @hanchiang made their first contribution in #1

Full Changelog: https://github.com/hanchiang/market-data-notification/commits/0.1.0