Proof-of-concept implementation of a potential new Supervisor feature
which allows arbitrary upstream ID token claims to be mapped into a
new top-level claim in the ID tokens issued by the Supervisor.
- Change update-codegen.sh script to also generated openapi code for the
aggregated API types
- Update both aggregated API servers' configuration to make them serve
the openapi docs for the aggregated APIs
- Add new integration test which runs `kubectl explain` for all Pinniped
API resources, and all fields and subfields of those resources
- Update some the comments on the API structs
- Change some names of the tmpl files to make the filename better match
the struct names
