Add KV session logic

[ishaan1013]

Add KV to database worker

On start:

Client

• Check if userId exists in KV store
  • If yes and running, alert that you can't have multiple sessions
  • If yes and not running, only alert if within 2 minutes of updatedAt
• Store userId (key), sandboxId, serviceName, running, and updatedAt when starting server

Server

• If running, calculate time to expiry and set a timeout
  • On timeout, emit message to frontend to disable access, and close the server

On delete:

• Get running to false, updatedAt to now