Fix Razor server shutdown on Windows.

On Windows, the Razor server correctly creates the pid file with
`FileAccess.Write` and `FileOptions.DeleteOnClose`.  This requires a share mode
of `FileShare.Write | FileShare.Delete` to open.  However, the
`dotnet build-server shutdown` command was opening the file with
`FileShare.Read`.  As a result, an `IOException` was being thrown and was not
handled.

This change first opens the file with the appropriate share access and also
properly handles a failure to access or read the contents of the pid file.

Additionally, an integration test was added to test that Razor server shutdown
works as expected.

Fixes #9158.

test/Microsoft.DotNet.Tools.Tests.Utilities/Commands/BuildServerCommand.cs

@@ -0,0 +1,20 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Microsoft.DotNet.Cli.Utils;
+
+namespace Microsoft.DotNet.Tools.Test.Utilities
+{
+    public sealed class BuildServerCommand : DotnetCommand
+    {
+        public override CommandResult Execute(string args = "")
+        {
+            return base.Execute($"build-server {args}");
+        }
+
+        public override CommandResult ExecuteWithCapturedOutput(string args = "")
+        {
+            return base.ExecuteWithCapturedOutput($"build-server {args}");
+        }
+    }
+}