corso

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## Description

Add backup format version information to the backups so that we can distinguish between backups which use a single file vs the ones that use both .data and .meta files.

Overrides https://github.com/alcionai/corso/pull/2297. I've also set it against `main` so that the diff shows up properly.
Ref: https://github.com/alcionai/corso/pull/2324#issuecomment-1409709118

## Does this PR need a docs update or release note?

- [x] ✅ Yes, it's included
- [ ] 🕐 Yes, but in a later PR
- [ ] ⛔ No 

## Type of change

<!--- Please check the type of change your PR introduces: --->
- [x] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup

## Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* fixes https://github.com/alcionai/corso/issues/2230
* https://github.com/alcionai/corso/issues/2253

## Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual (Tested manually, will add an e2e test in a followup)
- [ ] ⚡ Unit test
- [ ] 💚 E2E