React to HttpAbstractions namespace changes

- aspnet/HttpAbstractions#549 and aspnet/HttpAbstractions#592
- clean up `using`s

src/Microsoft.AspNetCore.Authentication.Twitter/TwitterHandler.cs

@@ -13,7 +13,6 @@ using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Authentication;
 using Microsoft.AspNetCore.Http.Features.Authentication;
-using Microsoft.AspNetCore.Http.Internal;
 using Microsoft.AspNetCore.WebUtilities;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Primitives;

src/Microsoft.AspNetCore.Authentication/HttpContextExtensions.cs

@@ -2,9 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Http.Features.Authentication;
-using Microsoft.AspNetCore.Http.Features.Authentication.Internal;
 
 namespace Microsoft.AspNetCore.Authentication
 {

src/Microsoft.AspNetCore.CookiePolicy/CookiePolicyMiddleware.cs

@@ -6,7 +6,6 @@ using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
-using Microsoft.AspNetCore.Http.Features.Internal;
 using Microsoft.Extensions.Options;
 
 namespace Microsoft.AspNetCore.CookiePolicy

test/Microsoft.AspNetCore.Authentication.Test/AuthenticationHandlerFacts.cs

@@ -11,7 +11,6 @@ using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Authentication;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Http.Features.Authentication;
-using Microsoft.AspNetCore.Http.Internal;
 using Microsoft.Extensions.Logging;
 using Xunit;
 

test/Microsoft.AspNetCore.Authentication.Test/Cookies/Infrastructure/CookieChunkingTests.cs

@@ -2,9 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Collections.Generic;
 using Microsoft.AspNetCore.Http;
-using Microsoft.AspNetCore.Http.Internal;
 using Xunit;
 
 namespace Microsoft.AspNetCore.Authentication.Cookies.Infrastructure

test/Microsoft.AspNetCore.Authentication.Test/TokenExtensionTests.cs

@@ -3,14 +3,12 @@
 
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.Linq;
 using System.Security.Claims;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Authentication;
 using Microsoft.AspNetCore.Http.Features.Authentication;
-using Microsoft.AspNetCore.Http.Features.Authentication.Internal;
-using Microsoft.AspNetCore.Http.Internal;
 using Xunit;
 
 namespace Microsoft.AspNetCore.Authentication