Fixes #34830

Fixes #36715

Fixes #30324

razor added new @code block. add support for new code block in roslyn.

for old razor version, IsCodeBlock won't get called since razor will not treat code in @code as C# code block, in new razor version where @code is added, razor will recognize it as C# code block and call us which we will in turn check new @code along with existing @ tags for code blocks.

Make Dispose analyzers (IDE0067 and IDE0069) more conservative

Fixes #34483, #36112

Change dotnet_diagnostic.*.severity settings to match code style

- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.19323.4

Support nullable variance in interface and partial method implementation.

Closes #35227.

* Update dependencies from https://github.com/dotnet/arcade build 20190620.1

- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.19320.1

* Bring changes from https://github.com/dotnet/arcade/pull/3076

* Update dependencies from https://github.com/dotnet/arcade build 20190621.75

- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.19321.75

* Update dependencies from https://github.com/dotnet/arcade build 20190622.2

- Microsoft.DotNet.Arcade.Sdk - 1.0.0-beta.19322.2

Update to Roslyn.Diagnostics.Analyzers 2.9.3

1. Make IDE0069 (DisposableFieldsShouldBeDisposed) conservative by bailing out on disposable types that don't have the Dispose implementation, but rely on base type implementing it and having virtual helper methods for dispose functionality

2. Make IDE0067 (DisposeObjectsBeforeLosingScope) conservative by bailing out on disposable objects that are passed as arguments to methods in metadata.

Requires updating to a new FlowAnalysisUtilities version.
Fixes #36498

Update Building, Debugging, and Testing on Windows.md

* added NFW to get some data on incremental parsing bug where source size and tree size is different

* more comments

Use IFeatureServiceFactory to disable async completion

Wire NullableWalker snapshotting to the public SpeculativeSemanticModel apis

Add some nullability tests for Generate Type and fix one bug

Closes https://github.com/dotnet/roslyn/issues/30316

The code style settings we already had in a .editorconfig file supplied
a set of terms to set different diagnostic severities. The terms don't
match the underlying compiler enum, but we will adopt them for
setting compiler diagnostic settings as well to keep the values
consistent inside a .editorconfig file.

Fixes https://github.com/dotnet/roslyn/issues/35690

Also add extension methods to help with nullability

* dotnet/master: (85 commits)
  Don't complete statement when typing semicolon inside comments in an argument list (#36521)
  Set focus to editor before finding text
  Add a bunch of nullability support to some code generation helpers
  Add 'annotations' and 'warnings' support to nullable directive (#36464)
  Fixed IDE services touching `notnull` constraint (#36508)
  Update compiler toolset to arcade version (#36549)
  Fix for 923157
  Do not include value types in NullableAttribute byte[] (#36519)
  Fix a deadlock in InvokeOnUIThread
  Apply a hang mitigating timeout to UI thread operations
  Move to a different lowering from for nullable value types to work around a bug in TransformCompoundAssignmentLHS. Addressed PR feedback.
  Fix stack overflow in requesting syntax directives (#36347)
  crash on ClassifyUpdate for EventFields (#35962)
  fixing bad merge with refactoring that was checked in later
  added basic completion statement telemetry
  Remove duplication in AbstractSymbolCompletionProvider.CreateItems
  Disable move type when the options service isn't present (#36334)
  Fix crash where type inference doing method inference needs to drop nullability
  Revert "Use IVsSolution to look up IVsHierarchy by project GUID (#35746)"
  Fix parsing bug in invalid using statements (#36428)
  ...

Closes #33807

Set focus to editor before finding text