* upstream/master: (37 commits)
  Lint
  Fix failure to apply timeout in WaitForAllAsyncOperations
  Additional code cleanup
  Fix file headers in default code cleanup
  Update TestRunner.cs (#46690)
  Make Format Document an explicit item in Code Cleanup
  Extract test helper GetDefaultDiagnosticAnalyzerService()
  Simplify type checks.
  Fix crash when typing in an indexer.
  Enforce DoesNotReturn on return; (#46659)
  Disable code fix assemblies during builds
  Expose generator internals: (#46296)
  Address feedback
  Address feedback + fix test
  Update to Microsoft.Net.Compilers.Toolset 3.8.0-2.20408.4
  Add work item attributes
  Add a new command line switch to skip analyzer execution
  Add restricted IVTs for IntelliCode
  Update to Microsoft.CodeAnalysis.Testing 1.0.1-beta1.20407.3
  Finish conversion to new test library
  ...

Remove prototypes and fix a small bug

Extract test helper GetDefaultDiagnosticAnalyzerService()

Fix failure to apply timeout in WaitForAllAsyncOperations

Fix crash when typing in an indexer.

File header cleanup

Closes #46487

* Update TestRunner.cs

* Update TestRunner.cs

Closes #43258

Change GacFileResolver.IsAvailable to check a type from System.Core

Fix failures to use VBCSCompiler.exe for Roslyn builds

Fix improper construction of DiagnosticAnalyzerService

Merge master to features/function-pointers

Add a new command line switch to skip analyzer execution

See #46684

Finish 'Generate Equals' conversion to new test library

Add restricted IVTs for IntelliCode

* upstream/master: (465 commits)
  Stop specifying Rich Nav's version of dotnet
  Fix nullable reference warning
  Fix up some calls to SymbolKey.Resolve now that it's annotated
  Remove try/catch of ArgumentException
  Null annotate SymbolKey
  Annotate Location.IsInSource as ensuring SourceTree is non-null
  Fix nullable annotation of Compilation.CreateErrorTypeSymbol
  Update null state for add/remove on field-like events (#46477)
  Throw IndexOutOfRangeException from BitVector.this[int] if index < 0 (#46627)
  Delete some dead support for changing legacy options
  Delete our use of Microsoft.VisualStudio.CodingConventions
  Fix crash in the preview of a code action that modified an .editorconfig
  Move null check above where the variable is used (#46558)
  Add integration test to configure diagnostic severity via editorconfig
  Disable a few Mac tests
  Consider nullability in conversion to constraint type (#46405)
  Added interpolated strings and tests
  Introduce request context (#46557)
  Simplify NativeIntegerAttribute encoding (#46522)
  Update extension getenumerator status. (#46607)
  ...

Fix couple of issues related to SerializableOptionSet which were leading to checkum validation asserts

* Expose generator internals:
- Add a new api + result objects to return generator driver internals
- Rework the way we handle exceptions, especially for syntax walk based operations
- Ensure we don't mix up generator and driver exceptions

Add CallingConventions to the public api

Null annotate SymbolKey and a bit more of the compiler

Add integration test to configure diagnostic severity via editorconfig

Stop specifying Rich Nav's version of dotnet

Delete our use of Microsoft.VisualStudio.CodingConventions

* Clarify tests.
* Remove a redundant condition.