## Description
In a backup operation, begins the operation by
retrieving all backup manifests and metadata
from prior operations.
## Type of change
- [x] 🌻 Feature
## Issue(s)
* #1725
## Test Plan
- [x] ⚡ Unit test
- [x] 💚 E2E
## Description
This PR uses a separate snapshot to store backup details instead of a Corso model (i.e. a kopia manifest).
Introduces a `StreamStore` that can be leveraged to store larger metadata objects. We can also leverage this
for incrementals or restartable backups going forward.
## Type of change
<!--- Please check the type of change your PR introduces: --->
- [x] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [ ] 💻 CI/Deployment
- [ ] 🐹 Trivial/Minor
## Issue(s)
<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* #1735
## Test Plan
<!-- How will this be tested prior to merging.-->
- [ ] 💪 Manual
- [x] ⚡ Unit test
- [x] 💚 E2E
