(GH-793) Use 2.0 Async method name

This commit renames methods to conform to version 2.0 naming standard;

* Async method names should be suffixed with Async

Author: glennsarti

src/PowerShellEditorServices.Protocol/Server/LanguageServer.cs

@@ -131,7 +131,7 @@ public void Start()
             this.messageHandlers.SetRequestHandler(
                 DocumentRangeFormattingRequest.Type,
                 this.HandleDocumentRangeFormattingRequest);
-            this.messageHandlers.SetRequestHandler(FoldingRangeRequest.Type, this.HandleFoldingRangeRequest);
+            this.messageHandlers.SetRequestHandler(FoldingRangeRequest.Type, this.HandleFoldingRangeRequestAsync);
 
             this.messageHandlers.SetRequestHandler(ShowOnlineHelpRequest.Type, this.HandleShowOnlineHelpRequest);
             this.messageHandlers.SetRequestHandler(ShowHelpRequest.Type, this.HandleShowHelpRequest);
@@ -1252,7 +1252,7 @@ await requestContext.SendResult(new TextEdit[1]
             });
         }
 
-        protected async Task HandleFoldingRangeRequest(
+        protected async Task HandleFoldingRangeRequestAsync(
             FoldingRangeParams foldingParams,
             RequestContext<FoldingRange[]> requestContext)
         {