## Description
Add ModTime to Exchange, OneDrive and SharePoint list stream items. This enables kopia-assisted incrementals for those items. Backup details still contains a complete set of information for all items in the backup regardless of if kopia uploaded data for the item or not.
Kopia-assisted incrementals does come with some caveats though. If changes are made to an item in M365 and that change does not cause the modified time reported by M365 to update, then the change will not be backed up. Currently, only marking an email as read/unread is known to hit this edge case.
This patch does not lazily fetch data from Graph API. This means that kopia may upload less data, but the same amount of data will still be pulled from Graph
## Type of change
- [x] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [ ] 💻 CI/Deployment
- [ ] 🐹 Trivial/Minor
## Issue(s)
* closes#622
## Test Plan
<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [x] ⚡ Unit test
- [ ] 💚 E2E
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