Setup semantic-release & CI

[schickling]

[jasonkuhrt]

We use circleci 2 and now 2.1 extensively at Dialogue where I work. There's a lot of nice things we can leverage out of it that graphqlgen* isn't yet, such as:

• leverage workflow to visualize the various checks tests builds publishes etc. being done
• split various checks/lints/tests into discrete workflow jobs (more parallelism but also granular pr check failure reporting)
• caching
• automatic test splitting

*Actually it would be a good topic for probably streamlining ci/d across prisma oss repos. For example custom orbs (reusable ci/d pipeline components) that encapsulate Prisma's ci/d-standards and make leverages workflows parallelism as painless/fun as possible. :)