Basic validation checks that make sure maintenance and retention options are consistent with each other. This at least makes sure retention is either enabled and maintenance extends locks or nothing is locked at all.
Going to be part of a set of PRs for validating the kopia config
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#### Does this PR need a docs update or release note?
- [ ] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [x] ⛔ No
#### Type of change
- [x] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [x] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup
#### Test Plan
- [ ] 💪 Manual
- [x] ⚡ Unit test
- [ ] 💚 E2E