https://github.com/kubernetes/enhancements/blob/master/keps/sig-storage/177-volume-snapshot/tighten-validation-webhook-crd.md
1. Ratcheting validation webhook server image
2. Controller labels invalid objects
3. Unit tests for webhook
4. Deployment README and example deployment method with certs
5. Update top-level README
Racheting validation:
1. webhook is strict on create
2. webhook is strict on updates where the existing object passes strict validation
3. webhook is relaxed on updates where the existing object fails strict validation (allows finalizer removal, status update, deletion, etc)
Additionally the validating wehook server will perform immutability
checks on scenario 2 above.
This dependency is problematic because of the many replaces it brings
with it. This makes it hard to import external-snapshotter in 3rd
party projects without having a lot of `replace` directives in those
projects as well.
The only usage of that import was to get two very simple utility
functions so I copied them over to this repo.
