## Description
`graph.Service -> graph.Servicer`, no other changes.
More compliant with golang naming standards,
and will allow us to eventually migrate the
Service struct out of connector and into graph.
## Type of change
- [x] 🐹 Trivial/Minor
## Issue(s)
* #1725
## Description
Move user discovery into a `discovery` package. Also use that to return user display name from `m365.Users()` call.
This will also allow us to remove `Users` from the GC struct going forward.
If this pattern works - will follow up with a similar change for `Sites()`.
## Type of change
<!--- Please check the type of change your PR introduces: --->
- [x] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [ ] 💻 CI/Deployment
- [ ] 🐹 Trivial/Minor
## Test Plan
<!-- How will this be tested prior to merging.-->
- [ ] 💪 Manual
- [x] ⚡ Unit test
- [ ] 💚 E2E