Fix visibility for tests

Author: shana

src/GitHub.VisualStudio/Services/UIProvider.cs

@@ -114,7 +114,7 @@ public T TryGetService<T>() where T : class
     /// This is a globally registered service (see `GitHubPackage`).
     /// If you need to access this service via MEF, use the `IUIProvider` type
     /// </summary>
-    internal class GitHubServiceProvider : IUIProvider, IDisposable
+    public class GitHubServiceProvider : IUIProvider, IDisposable
     {
         class OwnedComposablePart
         {

src/UnitTests/GitHub.App/Controllers/UIProviderTests.cs

@@ -23,7 +23,7 @@ public void ListenToCompletionDoesNotThrowInRelease()
     {
         var provider = Substitutes.GetFullyMockedServiceProvider();
 
-        using (var p = new UIProvider(provider))
+        using (var p = new GitHubServiceProvider(provider))
         {
 #if DEBUG
             Assert.ThrowsAny<InvalidOperationException>(() =>