Refactor using golang

[olevski]

This should improve performance and resource efficiency.

The refactored code should have:

• swagger page (ideally using a spec-first approach where code is generated from the api spec and not the other way around)
• clear separation of endpoints for login vs endpoints used by traefik
• documentation of the logic/methodology for authentication and token lifetime (as short as possible)
• locking to ensure that race conditions of refreshing a token with the same refresh tokens twice does not happen - redis provides a locking mechanism that may be used across different replicas of the gateway
• test coverage of at least 75%