<!-- PR description-->
One of the 2 remaining setup PRs before we can introduce local storage repos.
**Changes:**
1. Read storage provider(`provider`) from config file except for `repo init * ` or `repo connect *` commands.
2. Apply flag overrides based on provider type( e.g. `S3FlagOverrides` if provider is `S3`)
3. Propagate storage provider type to functions which read/write config. These functions arbitrate on config hierarchy - flags, env, config file, in that order.
**Reasons**
* Reason 1 is needed is because config file is the source of truth for storage provider for all commands except `repo init` or `repo connect`. In the exception cases, we pick the provider in command (e.g. `s3`) as the source of truth. e.g. consider a `repo init s3`, followed by `repo init filesystem`.During `repo init filesystem`, config file would indicate `S3` provider, but the correct behavior here is to select `filesystem` provider.
* One alternative was to push provider from the init/connect cmds into an override flag, and let the config code decide on hierarchy. However, this felt hacky. provider here is not a flag to begin with. It's part of init/connect commands.
---
#### Does this PR need a docs update or release note?
- [ ] ✅ Yes, it's included
- [x] 🕐 Yes, but in a later PR
- [ ] ⛔ No
#### Type of change
<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [x] 🧹 Tech Debt/Cleanup
#### Issue(s)
<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* https://github.com/alcionai/corso/issues/1416
#### Test Plan
<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E
#### Does this PR need a docs update or release note?
- [x] ⛔ No
#### Type of change
- [x] 🧹 Tech Debt/Cleanup
#### Issue(s)
* #3988
#### Test Plan
- [x] ⚡ Unit test
- [x] 💚 E2E
#### Does this PR need a docs update or release note?
- [x] ⛔ No
#### Type of change
- [x] 🤖 Supportability/Tests
#### Test Plan
- [x] ⚡ Unit test
- [x] 💚 E2E
#### Does this PR need a docs update or release note?
- [x] ⛔ No
#### Type of change
- [x] 🌻 Feature
#### Issue(s)
* #3989
#### Test Plan
- [x] 💪 Manual
- [x] ⚡ Unit test
This borrows a lot of the core logic from OneDrive as the internal structure is mostly the same.
<!-- PR description-->
Prev: https://github.com/alcionai/corso/pull/3822
---
#### 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
- [ ] 🤖 Supportability/Tests
- [ ] 💻 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/3823
#### Test Plan
<!-- How will this be tested prior to merging.-->
- [ ] 💪 Manual
- [x] ⚡ Unit test
- [ ] 💚 E2E
This adds the final piece to enable OneDrive exports. The CLI interface which consumes NewExport interface from Repository and lets the user to export and write the contents in a backup to the local filesystem.
<!-- PR description-->
Prev: https://github.com/alcionai/corso/pull/3821
Next: https://github.com/alcionai/corso/pull/3824
---
#### 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
- [ ] 🤖 Supportability/Tests
- [ ] 💻 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. -->
* https://github.com/alcionai/corso/pull/3797
* https://github.com/alcionai/corso/issues/3670
#### Test Plan
<!-- How will this be tested prior to merging.-->
- [ ] 💪 Manual
- [x] ⚡ Unit test
- [ ] 💚 E2E
