Gen Lu

And a few other clean-ups

### Describe the bug Hi, I'm a developer in Visual Studio, and I'm seeing unhandled `System.IndexOutOfRangeException` from AvaloniaVS that might have caused issue with IntelliSense in VS Here's the stacktrace:...

Exclude assemblies shared by .NET ServiceHub host

2

[Validation build](https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_build/results?buildId=9441189&view=results) [Insertion](https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/545087)

Migrate Codelens provider to .NET

4

val build: ~~https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_build/results?buildId=10026486&view=results~~ ~~https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_build/results?buildId=10035404&view=results~~ https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/586489

Remaining issues for "sync namespace" refactoring

1

Using this to track some of the remaining issues for the "Sync namespace" refactoring. - [ ] Fix undo of move file - [x] Make this refactoring work on CPS...