Add Missing Cases for Nullable Enums

Annotate implementations of IDynamicTypeSymbol

* Rework build definitions to accept VS optprof drop

Save serializable options on the solution snapshot

Fix race condition in CodeFixService

* Improve nullable analysis of local functions

This design tries to meld better analysis of nullable reference types in
local functions with performance. To keep the common case one pass,
local functions are analyzed using the starting state that is an
intersection of all the states before its usages (calls, delegate
conversions, etc), but the results of variables made nullable or
non-nullable inside the local function do not propagate to the callers.

* Respond to PR comments

Ensure that we process diagnostics ordered by their span and then diagnostic ID. This fixes a race condition seen in intermittent failures for ConfigureCodeStyleOptionValueAndSeverity where the order of configuration/suppression fixes is non-deterministic

Revert "Merge pull request #40765 from dibarbet/revert_use_index"

Annotate implementations of IAliasSymbol

This reverts commit a9989fd2, reversing
changes made to 9ba266a7.

Unskip and fix integration test

Update configs for preview 2 snap

Move run code actions back to liveshare layer so that we can switch t…

Revert "Merge pull request #40410 from sharwell/use-index"

* 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

remove preview 1 publishing

Closes #38198

Annotated SyntaxList

This reverts commit 5c179e87, reversing
changes made to d3400922.

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