Implement subscriptions

[blms]

• Remember to set reconnect: true in /src/state/client.js > subscriptionLink
  Possibly with this guide

[blms]

Coming in a later version of prisma: prisma/prisma#298

[blms]

Seems to be available now, just need to set up:
https://nexusjs.org/docs/adoption-guides/nexus-framework-users#subscriptions-server