## Description
Three changes: adds a LargeItem servicer to
the exchange api client. Migrates attachment
downloads in mail and events out of serialize
and into the GetItem func. Finally, utilizes the
largeItem servicer to download attachments,
instead of the standard servicer.
A follow-up PR will add mocked test cases for
these changes.
## Does this PR need a docs update or release note?
- [x] ✅ Yes, it's included
## Type of change
- [x] 🌻 Feature
## Issue(s)
* #2299
## Test Plan
- [x] 💚 E2E
0d8eb8f4fa