Port to TypegraphQL-Prisma

[oohwooh]

This would be a reasonably large undertaking, and is not a priority by any means, but it would be a worthwhile endeavor imo.

We would need to add CustomResolvers for all the current resolvers to not break backwards-compatibility.

The main benefits from doing this:

• Ease of future development (both to showcase-gql and any service that makes use of it)
• Consistency with other services
• Small enough to be a good first leap into porting the rest of our gql services to typegraphql-prisma