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
---
#### 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
metadata is too much data to be useful to an end user, meanwhile err is getting clobbered.
before
```
Error: Unable to complete backup
Message: <nil>
Metadata:{"assist_bases":"0","backup_id":"40940295-3611-42fb-ac27-5b80691ba793","base_backup_id":"832fff09-4988-4a3e-a0d0-4e51b197ea14","can_use_metadata":"true","can_use_previous_backup":"true","categories":"[Chats]","clues_trace":"c3bbd0e6","collection_count":"2","disable_assist_backup":"false","incremental":"true","merge_bases":"1","repo_ref":"fb8afbaa-e94c-4ea5-8a8a-24aff04d7874/chats/311d2a89-4c80-4da4-86ef-a08d8d6f0f94/chats/19:311d2a89-4c80-4da4-86ef-a08d8d6f0f94_817c2506-de4a-4795-971e-371ea75a03ed@unq.gbl.spaces","resource_owner_id":"311d2a89-4c80-4da4-86ef-a08d8d6f0f94","resource_owner_name":"rfinders@10rqc2.onmicrosoft.com","resource_owner_selected":"rfinders@10rqc2.onmicrosoft.com","service":"service(5)","tenant_id":"fb8afbaa-e94c-4ea5-8a8a-24aff04d7874"}
```
after
```
Error: Unable to complete backup
Cause: running backup: merging details: merging merge backup base details: getting updated info for entry: getting previous item location: unable to extract LocationRef from RepoRef
```
---
#### Does this PR need a docs update or release note?
- [x] ⛔ No
#### Type of change
- [x] 🧹 Tech Debt/Cleanup
#### Test Plan
- [x] 💪 Manual
