Add completion spec: openshift (oc)

Add a comprehensive completion spec for the OpenShift CLI (oc) with:

- JSON spec covering all 62 oc subcommands, including shared kubectl
  commands and OpenShift-specific ones (login, new-app, new-build,
  start-build, adm, project, etc.)
- Generators for dynamic completions:
  - Reuses kubectl generators for shared Kubernetes resources
  - oc_builtin_completion using oc's Cobra __complete protocol
  - projects generator for oc project switching
  - build_configs generator for oc start-build

Closes APP-3507

Co-Authored-By: Oz <oz-agent@warp.dev>

Author: oz-agent