Add MEF metadata to IDeferredQuickInfoContentToFrameworkElementConverter

Merge dev15.6-preview2 to master

LOC CHECKIN | dotnet/roslyn – master | 20171222

When I added this interface, I had the implementations expose their
applicable type not by metadata, but by simply calling a method on
the instance. This is problematic if the implementation is in a
different assembly as we'll load it too early. This is causing F#
to load when they shouldn't.

This is intended as a temporary shim that fixes the perf load for
the F# case (the only current exporter of these outside the Roslyn
repo itself) without forcing an interface change. This will get deleted
soon enough once we migrate to newer Quick Info APIs.

This change removes the following APIs:
- TypeSymbol.BaseType
- TypeSymbol.Interfaces
- TypeSymbol.AllInterfaces
- NamedTypeSymbol.TypeArguments
- TypeParameterSymbol.ConstraintTypes

These APIs simply delegate the work to APIs with "NoUseSiteDiagnostics" suffix and are not supposed to be used inside compilers. They were left in the code-base because they used to be part of the public surface and the names were nicer, but they are no longer part of the public surface.

* Suggest stackalloc keyword in Span legal places

* Address PR Comments

* More PR Feedback

* Clean up

Remove the TestUtilities Desktop / CoreClr projects

The conditional build of net45 was added when we didn't support any
desktop targetframeworks on Linux. Now that it's supported we should be
building all flavors of the utilities there.

* Pass in optional arguments by ref

* IOperation tree tests

* PR Comments

Fix the blob publishing