Use GitOps Toolkit

[luxas]

This PR is a first draft towards re-using the Kubernetes API machinery for our files. In order to combine this with (automatic) GitOps for the server-side component serving the GraphQL API for the website, we can use https://github.com/weaveworks/gitops-toolkit that I built for exactly this purpose latest summer.

FWIW: Most of this code is autogenerated.

Progress:

• Initial API types for internal & v1alpha1
• Use spec/status consistently, in a way we want to
• Make use of ObjectMeta correctly, so that we don't duplicate information
• Port the generator to be able to use these new types
  • Implement a lazy loading mechanism of the company/speaker references
• Hook this up to the server-side component, which listens to a git repo for changes
• Calculate the stats in a different place
• Maybes:
  • Don't force us to use UID/created timestamps here
  • Instead of using the general-purpose ManifestStorage implementation for the generator, use a purpose-built Meetup(Raw)Storage implementation for our purposes
  •  Create types CompanyList and SpeakerList