[meta] Create Sync Server Prototype

[bbangert]

Creating a sync server prototype and retain existing handling and response characteristics with the existing Python version.

All of these components should behave in a similar compatible manner.

• Request validation/extraction logic
  • Port default validators
  • Port get/delete collection/bso validators
  • Port put validators
  • Create precondition check middleware
  • Port batch validator
• Error handling for responses
  • Use failure crate everywhere
• Logging & Sentry Usage
  • Add Sentry
• Database methods (MySQL)
  • Support a mysql backend
  • Create a canonical session timestamp
  • Implement batch db calls
  • Implement collection-level locking
  • Integrate db layer and handlers w/ a Middleware/Extractor
• Handler (view) logic to manipulate request data to db calls

[pjenvey]

Minus some e2e test failure issues we've finished the initial prototype