[Feature]: Rebuild join-rematch for GameState Api

[Haviles04]

Feature Summary

We need to rebuild the join-rematch to work in the new GameState Api

Detailed Description

We need to build a new endpoint to replace the current join-rematch endpoint. Instead of populateGame we will have to unpack the most recent gameStates object and publish that game state. See the spec for a general overview of the API, its underlying motivations, and the development approach.