* dotnet/master: (345 commits)
  Update indexers based on analyzer receiver (#34134)
  Skip test DecimalBinaryOp_03 (#34199)
  Remove earlier nullable documentation (#34153)
  Rewrite FindReferencesTests as theories
  Apply a hang mitigating timeout to ExecuteCommand
  Warn on __refvalue null dereference: (#34135)
  Update dependencies from https://github.com/dotnet/arcade build 20190312.7 (#34112)
  Update vs branch for 16.1
  Fix struct layout error when nullable enabled: (#34128)
  Remove IgnoreInsignificantNullableModifiersDifference (#34096)
  Add the correct nullable annotations to generated iterator code (#33986)
  Move Rename implementation to new fully loaded document API.
  handle encapsulate field command
  change the way extract method handle partial load
  handle orangize document
  Add back Go to definition method.
  Revert "Move Go to definition to new fully loaded document API."
  Revert "Move Find references implementation to new fully loaded document API."
  Move Find references implementation to new fully loaded document API.
  Track nullable state across boxing conversions (#34087)
  ...

Move to .NET Core 3.0 SDK

Allow NuGet within the IDE

Fix few false positives in unused value assignment analyzer

This change updates the following dependencies
- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.19167.10

Workaround a deadlock caused by watching .editorconfigs

Simplify VisualStudioWaitIndicator

Works around Microsoft/msbuild#4239.

Enable some custom modifier tests on Mono

Remove unused ICommentUncommentService.

Fixes one bug around dropping suppression for a tuple conversion.

Closes #32553

Fix typo

Related issues:

- https://github.com/dotnet/roslyn/issues/34211
- https://github.com/dotnet/cli/issues/10989

It appears fast enough to use now. 🎉