chore: updates based on review feedback
chore: updates based on review feedback

- Rename 'current_key_id' to `key_id`
- Rename metadata to annotations in proto
- Use byes for annotations value instead of string
- Make beta/GA requirements as TBD

Signed-off-by: Anish Ramasekar <a572ede9ce1358d1136f42c34aa7ee01a1b1a835@gmail.com>

kubernetes/enhancements,kubernetes/enhancements,kubernetes/enhancements