Include local exports when targeting a MEF component

[jcansdale]

When running ad-hoc tests on a VS SDK MEF component, make it so that locally defined MEF components are visible to the ImportingConstructor of the target component.

For example, executing the Go method below using Test With > In-Proc (VS SDK) should output the ExportedComponent:

    [Export]
    public class ComponentWithImport
    {
        ExportedComponent component;

        [ImportingConstructor]
        public Foo(ExportedComponent component)
        {
            this.component = component;
        }

        public void Go()
        {
            Console.WriteLine(component);
        }
    }

    [Export]
    public class ExportedComponent
    {
    }

[jcansdale]

Dupe of #132