Add support for adding NuGet references through add-using.

Fixes https://github.com/dotnet/roslyn/issues/9148
Fixes https://github.com/dotnet/roslyn/issues/8787
Fixes https://github.com/dotnet/roslyn/issues/8779
Fixes https://github.com/dotnet/roslyn/issues/8777
Fixes https://github.com/dotnet/roslyn/issues/8771
Fixes https://github.com/dotnet/roslyn/issues/8756
Fixes https://github.com/dotnet/roslyn/issues/8754
Fixes https://github.com/dotnet/roslyn/issues/8706
Fixes https://github.com/dotnet/roslyn/issues/8705
Fixes https://github.com/dotnet/roslyn/issues/8702
Fixes https://github.com/dotnet/roslyn/issues/8693
Fixes https://github.com/dotnet/roslyn/issues/8687
Fixes https://github.com/dotnet/roslyn/issues/8686
Fixes https://github.com/dotnet/roslyn/issues/8684
Fixes https://github.com/dotnet/roslyn/issues/8683
Fixes https://github.com/dotnet/roslyn/issues/8682
Fixes https://github.com/dotnet/roslyn/issues/8681
Fixes https://github.com/dotnet/roslyn/issues/8680
Fixes https://github.com/dotnet/roslyn/issues/8679
Fixes https://github.com/dotnet/roslyn/issues/8678
Fixes https://github.com/dotnet/roslyn/issues/8571
Fixes https://github.com/dotnet/roslyn/issues/8516

Attempt to detect one possible cause for the rename test flakiness

[Ask Mode] Add some missing syntax kinds to VB MemberSemanticModel.IsStandaloneStatement

Mark methods as Obsolete.

Fixes #9054

XmlThreadSafetyElement param names

Add public sign to help for csc & vbc

This can be used to determine if a reference-assembly hit in Elfie is actually
valid for the project it is found in.

Revert "Fix EnC for compilations with dependencies using time-based versioning"

This service provdies the facilities for searching for potential nuget packages
that will resolve code issues.

This interface is used to provide facilities for querying Nuget information
on any thread.  The normal nuget apis are thread affinitized and that's
problematic for the code actions we want running on the background.

Logical sorting thinks of '10' as greater than '2' even though
it starts with '1' and normally '1' is less than '2'.

This is necessary so that the light-bulb will dismiss with long running
suggested actions.  Otherwise, it will stick on the screen for the duration
of 'Invoke()'.

Note: integration tests already do a 'wait' after invoking to make sure
the light bulbs have finished.  So they are unaffected by this.

Always use an absolute path for keyfile with public sign

Changing the names of the parameters to `isStatic` and `isInstance` to be consistent with the naming guidelines of boolean parameters.

This reverts commit d43d4780.

Hook-up OperationWalker in compiler tests

Fix reset interactive imports