"Use System.Index/Range" feature should recognize the same "implicit index/range support" the language has.

Fixes #10492

Fixes #38586

Local function control flow analysis should now use the analysis walker from the base
class instead of defining its own.

Fixes #39946

Merge features/localsinit into master

Fixes #40129

Update 'Populate switch' to support switch-expressions.

Unskip tests that were skipped due to adaptive formatting triggering

Null annotate IEditorFormattingService and the consuming command handler

Added System.Index and System.Range

* Update dependencies from https://github.com/dotnet/arcade build 20191214.1

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.19614.1

* Update dependencies from https://github.com/dotnet/arcade build 20191215.1

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.19615.1

Add tests for: Update 'Populate switch' to support switch-expressions.

NullableAnnotation on a type symbol returned by TypeInfo should match corresponding FlowState. (#40338)

Fixes #40051.

Insert using trailing separator for consistency with 'Convert switch statement to expression' action

* Use embedded resources for ProximityExpressionsGetter tests

* Move breakpoint resolver down into Features

* Update dependencies from https://github.com/dotnet/arcade build 20191211.6

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.19611.6

* Update dependencies from https://github.com/dotnet/arcade build 20191212.1

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.19612.1

* Update dependencies from https://github.com/dotnet/arcade build 20191213.1

- Microsoft.DotNet.Arcade.Sdk - 5.0.0-beta.19613.1

Merge release/dev16.4 to master

Nullable progress: Enable nullable fully for TypeSymbolExtensions

Pool intermediary allocations when generating unique names for features.

Add xml documentation for IsKind and Kind extension methods

Switch to iterative algorithm to prevent stack overflows.