Add a flag the user can specify to get kopia's logs added to the corso log file. Unfortunately, not all output from kopia is prefixed with the module it came from.
Sample log output with the new flag and log level debug (all debug level output from kopia)
```text
2023-06-22T16:21:48.022-0700 INFO observe/observe.go:195 done - Connecting to repository {"acct_provider": "M365", "acct_id": "xxxxxxxx-yyyy-zzzz-0000-111111111111", "storage_provider": "S3"}
2023-06-22T16:21:50.495-0700 DEBUG kopia-lib/kopia/repo repo/open.go:495 throttling limits from connection info {"limits": {}}
2023-06-22T16:21:50.496-0700 DEBUG refreshing committed state because it's no longer valid (now 2023-06-22 16:21:50.496029 -0700 PDT, valid until 0001-01-01T00:00:00Z)
2023-06-22T16:21:50.496-0700 DEBUG refreshAttemptLocked
2023-06-22T16:21:50.593-0700 DEBUG ranges: []
```
---
#### 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
- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [x] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [ ] 🧹 Tech Debt/Cleanup
#### Issue(s)
* #3528
#### Test Plan
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E
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