Fix dependencies in InlineCommentMarginProvider

Lazily load `IPullRequestSessionManager` in `InlineCommentMarginProvider` to prevent loading the kitchen sink on VS startup.

Author: grokys

src/GitHub.InlineReviews/InlineCommentMarginProvider.cs

@@ -28,27 +28,43 @@ internal sealed class InlineCommentMarginProvider : IWpfTextViewMarginProvider
         const string MarginName = "InlineComment";
         const string MarginPropertiesName = "Indicator Margin"; // Same background color as Glyph margin 
 
+        readonly IGitHubServiceProvider serviceProvider;
         readonly IEditorFormatMapService editorFormatMapService;
         readonly IViewTagAggregatorFactoryService tagAggregatorFactory;
         readonly IInlineCommentPeekService peekService;
-        readonly IPullRequestSessionManager sessionManager;
         readonly IPackageSettings packageSettings;
+        IPullRequestSessionManager sessionManager;
 
         [ImportingConstructor]
         public InlineCommentMarginProvider(
+            IGitHubServiceProvider serviceProvider,
             IEditorFormatMapService editorFormatMapService,
             IViewTagAggregatorFactoryService tagAggregatorFactory,
             IInlineCommentPeekService peekService,
-            IPullRequestSessionManager sessionManager,
             IPackageSettings packageSettings)
         {
+            this.serviceProvider = serviceProvider;
             this.editorFormatMapService = editorFormatMapService;
             this.tagAggregatorFactory = tagAggregatorFactory;
             this.peekService = peekService;
-            this.sessionManager = sessionManager;
             this.packageSettings = packageSettings;
         }
 
+        IPullRequestSessionManager SessionManager
+        {
+            get
+            {
+                // Lazily load the pull request session manager to prevent all of our assemblies
+                // being loaded on VS startup.
+                if (sessionManager == null)
+                {
+                    sessionManager = serviceProvider.GetService<IPullRequestSessionManager>();
+                }
+
+                return sessionManager;
+            }
+        }
+
         public IWpfTextViewMargin CreateMargin(IWpfTextViewHost wpfTextViewHost, IWpfTextViewMargin parent)
         {
             if (IsMarginDisabled(wpfTextViewHost))
@@ -95,7 +111,7 @@ void TrackCommentGlyph(IWpfTextViewHost host, UIElement marginElement)
 
         bool IsMarginVisible(ITextBuffer buffer)
         {
-            if (sessionManager.GetTextBufferInfo(buffer) != null)
+            if (SessionManager.GetTextBufferInfo(buffer) != null)
             {
                 return true;
             }