Pull into separate PR so we can start merging things separately.
`BackupBases` sourced from branch `backup_bases_changes`
`model.go` sourced from branch `partial_bup`
mock backup bases sourced from branch `backup-details-merge`
---
#### 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
- [ ] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup
#### Test Plan
- [ ] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E