* Adds nullability, removes dead code.

* Clean up RemoteHostClient exception and lifetime handling

* Nullables

* JsonRpcEx disposal cleanup

* Nullables

* Refactor abstract JsonRpcEx to sealed RemoteEndPoint

* Use RemoteEndPoint for ServiceHub services

* Move ctor

* Use RemoteEndPoint in ServiceHubRemoteHostClient

* Minor cleanup of log messages

* JsonRpcTargetOptions

* Use RemoteEndPoint in CodeLens, tests

* Inline Extensions.InvokeAsync methods into RemoteEndPoint

* Remove unnecessary invoke methods

* Unify exception handling

* Allow null arguments in remote invocation

* Simplify ClientDirectStream

* Fold ClientDirectStream and ServerDirectStream into RemoteEntryPoint

* Feedback

* Fix test

Annotated SyntaxList

fixed DeclarationNameCompletionProvider when used via Nuget package

Fixed handling of variable declarations inside of for loops in related code fixers

Fixes #40295

Fixes #31269

Fixes #39264

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.20054.1

Obsolete non-.editorconfig 'simplification options'.  

* Update dependencies from https://github.com/dotnet/arcade build 20200102.1

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.20052.1

* Update dependencies from https://github.com/dotnet/arcade build 20200103.2

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.20053.2

Implement support for CodeRefactoringProvider in NuGet packages

Fix cases where the simplification system doesn't simplify properly.

Fix for extract method crashes when extracting an invalid using statement

Begin migration to ILanguageClient for liveshare

The suppression in `SyntaxList` is necessary in order to meet
the API contract. Filed an issue for follow up

https://github.com/dotnet/roslyn/issues/40733

Co-Authored-By: NSam Harwell <sam@tunnelvisionlabs.com>

Don't use syntax context cache when the task is cancelled.