various tidbits of data cleanup before moving forward with adding export behavior to groups.
* move duplicate collections mocks into data/mock
* move the export collection struct into pkg/export (to prevent future duplicates in the next PR)
* rename export.Collection to Collectioner, because it's an interface.
* some other non-logic rearrangement
---
#### Does this PR need a docs update or release note?
- [x] ⛔ No
#### Type of change
- [x] 🧹 Tech Debt/Cleanup
#### Issue(s)
* #3991
#### Test Plan
- [x] ⚡ Unit test
- [x] 💚 E2E
Update the API for Item.Info to return an error.
This can then be leveraged to add lazy readers
to exchange backups
See #2023 for more info on how to add lazy
readers to exchange
---
#### 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
- [ ] 🤖 Supportability/Tests
- [ ] 💻 CI/Deployment
- [x] 🧹 Tech Debt/Cleanup
#### Issue(s)
* #2023
#### Test Plan
- [ ] 💪 Manual
- [x] ⚡ Unit test
- [x] 💚 E2E
A Stream is a continuous transmission of data.
An item is a single structure. Crossing the two
definitions generates confusion.
Primarily code movement/renaming. Though there
is also some reduction/replacement of structs
where we'd made a variety of testable Item implementations
instead of re-using the generic mock.
---
#### Does this PR need a docs update or release note?
- [x] ⛔ No
#### Type of change
- [x] 🧹 Tech Debt/Cleanup
#### Test Plan
- [x] ⚡ Unit test
- [x] 💚 E2E
