Add events

[YanickSchraner]

We want to introduce a new events issue.
The goal of this issue is, that we can notify the user if new interesting events happened.
This can be if a user got mentioned in a comment, his content got rejected, new content has to be translated into his translator language, new content has to be reviewed, etc.
For this use case, we want to add a new event table which stores a link to the affected component, links the event to the correct users, stores the event type and status (open, resolved).
We want to use subscriptions from the UI side if possible, to seamlessly update the web app.

[dafrie]

With subscriptions the GraphQL spec is meant, which is typically via Websockets.

See here (Client Side): https://www.apollographql.com/docs/react/advanced/subscriptions
For Django/Graphene, I guess we have to use another module such as: https://github.com/eamigo86/graphene-django-subscriptions

[worxli]

Use hasura.