This is now annotated as non-null, so the check is pointless.

These are all functions are supposed to work equally well with
regular documents, additional documents, and analyzer config documents.
However, they were all calling GetDocument that would only work with
the first kind.

The annotation is for the most part straightforwad. This removes a hack
where rather than passing some things through the VisualStudioProject
constructor, we just assigned some properties after creation. This
is now cleaned up since it made annotation problematic.

This wasn't necessarily safe -- if we did get a null for
HostDiagnosticUpdateSource, then any analyzers that had to report
loading issues would have thrown NullReferenceExceptions. This replaces
the use with an existing mock.

The error list includes VSIX name in the tool name displayed in error list for diagnostics from analyzers loaded from VSIX.
It doesn't seem displaying the package name is worth the extra complexity, especially since
moving these analyzers to Solution snapshot would require re-implementing this tracking in another way.

Use helper extension to simplify code.

Fix issue #42014 typo in VisualBasic\Portable\Binder CheckOverflow Property.

Always try to register the EditorConfigDocumentOptionsProvider

Properly simplify (this) expressions.

Infer proper types within tuples.

Adjust cases where we offer ?.Invoke

* Add dotnet-tools feed

* Update PDB Converter to 1.1.0-beta2-20115-01

* Remove symreader-converter myget feed

* Add dotnet5 feed

* Remove symreader, symreader-portable, sourcelink myget feeds

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.20151.1

Add test to demonstrate proper behavior.

Add test to validate proper intellisense.

Update src/Workspaces/SharedUtilitiesAndExtensions/Workspace/CSharp/LanguageServices/CSharpTypeInferenceService.TypeInferrer.cs
Co-Authored-By: NSam Harwell <sam@tunnelvisionlabs.com>