Summary:
Using `client-gen` requires apis to be in `<groupname>/<versionname>`
This is the folder structure used by most CRDs (I looked at etcd, jaeger, nats)
and so let's follow the same.

Test Plan: N/A. Moving files around.

Reviewers: michelle, philkuz

Reviewed By: michelle

Differential Revision: https://phab.corp.pixielabs.ai/D9693

GitOrigin-RevId: b693de36f511936ca6569509cb770da675470d76