Merge release/dev16.8 to master

Classify init accessor as returnable construct

Fix build breaks

Enable nullability by default in Roslyn

Update TypeImportCompletionProviderTests with records

Delete unused method

Merge release/dev16.8 to master

Implement redundant equality analyzer

Remove readonly on auto-property when a setter is needed

Add records support in navigate to

Fix typo in public API doc

* Prevent potential deadlocks when reading/writing assets

* Fix

* Handle cancellation during reading version bytes

* Fix

* Make sure to complete the pipe reader/writer even when canceling

* Fix

* Feedback

* Always complete reader, complete writer on error

* Fix comment

* Reorder conditions in exception handler

* Feedback

* Only treat OCE triggred by incorrect token as critical error in debug builds

* Feedback

* Logging

Switch internal type to use immutable arrays.

Mark all APIs as shipped for the 16.8 release.

[master] Update dependencies from dotnet/roslyn

Ensure IServiceBroker is used on a background thread

Disable hash collision resistance for user data

Provide required callback targets

Fix xml attribute name classification

Expands #47903 to other calls to GetProxyAsync.