Added ObjectPool to the solution so I could run in VS (#24141)

src/Hosting/Hosting.slnf

@@ -27,7 +27,8 @@
       "src\\Servers\\Kestrel\\Kestrel\\src\\Microsoft.AspNetCore.Server.Kestrel.csproj",
       "src\\Servers\\Kestrel\\Core\\src\\Microsoft.AspNetCore.Server.Kestrel.Core.csproj",
       "src\\Servers\\Kestrel\\Transport.Sockets\\src\\Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.csproj",
-      "src\\Servers\\Connections.Abstractions\\src\\Microsoft.AspNetCore.Connections.Abstractions.csproj"
+      "src\\Servers\\Connections.Abstractions\\src\\Microsoft.AspNetCore.Connections.Abstractions.csproj",
+      "src\\ObjectPool\\src\\Microsoft.Extensions.ObjectPool.csproj"
     ]
   }
 }

src/Hosting/Hosting/src/GenericHost/GenericWebHostBuilder.cs

@@ -14,7 +14,6 @@ using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Hosting;
-using Microsoft.Extensions.ObjectPool;
 
 namespace Microsoft.AspNetCore.Hosting
 {

src/Hosting/Hosting/src/WebHostBuilder.cs

@@ -15,7 +15,6 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.ObjectPool;
 
 namespace Microsoft.AspNetCore.Hosting
 {

src/Hosting/Hosting/test/WebHostBuilderTests.cs

@@ -21,7 +21,6 @@ using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Extensions.Logging.Testing;
-using Microsoft.Extensions.ObjectPool;
 using Xunit;
 
 [assembly: HostingStartup(typeof(WebHostBuilderTests.TestHostingStartup))]