Change the namespace to be without "Runtime"

Author: Yang Lyu

src/Microsoft.VisualStudio.Web.BrowserLink/BrowserLinkMiddleWare.cs

@@ -6,7 +6,6 @@
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Headers;
 using Microsoft.AspNetCore.Http.Features;
-using Microsoft.VisualStudio.Web.BrowserLink.Runtime;
 
 namespace Microsoft.VisualStudio.Web.BrowserLink
 {

src/Microsoft.VisualStudio.Web.BrowserLink/Common/ArteryConstants.cs

@@ -1,5 +1,3 @@
-using System;
-
 namespace Microsoft.VisualStudio.Web.BrowserLink
 {
     /// <summary>

src/Microsoft.VisualStudio.Web.BrowserLink/SendFilesWrapper.cs

@@ -1,14 +1,10 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
+using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
-using Microsoft.Extensions.FileProviders;
 
-namespace Microsoft.VisualStudio.Web.BrowserLink.Runtime
+namespace Microsoft.VisualStudio.Web.BrowserLink
 {
     internal class SendFilesWrapper : IHttpSendFileFeature
     {