Do not modify shared options in Notifications test

These tests were modifying a shared options object and causing
indeterminate results based on current running of other tests. I'm not
sure what changed (.Net 4.8? Visual Studio 2019?) to make them fail now
but not before.

Tests/Tests.Shared/WebSSO/SignInCommandTests.cs

@@ -79,14 +79,15 @@ public void SignInCommand_Run_Calls_NotificationForAbsoluteUrl()
             var httpRequest = new HttpRequestData("GET", new Uri($"http://localhost/signin?ReturnUrl={absoluteUri}"));
             var validateAbsoluteReturnUrlCalled = false;
 
-            Options.FromConfiguration.Notifications.ValidateAbsoluteReturnUrl =
+            var options = StubFactory.CreateOptions();
+            options.Notifications.ValidateAbsoluteReturnUrl =
                 (url) =>
                 {
                     validateAbsoluteReturnUrlCalled = true;
                     return true;
                 };
 
-            Action a = () => new SignInCommand().Run(httpRequest, Options.FromConfiguration);
+            Action a = () => new SignInCommand().Run(httpRequest, options);
 
             a.Should().NotThrow<InvalidOperationException>("the ValidateAbsoluteReturnUrl notification returns true");
             validateAbsoluteReturnUrlCalled.Should().BeTrue("the ValidateAbsoluteReturnUrl notification should have been called");
@@ -100,14 +101,15 @@ public void SignInCommand_Run_DoNotCalls_NotificationForRelativeUrl()
             var httpRequest = new HttpRequestData("GET", new Uri($"http://localhost/signin?ReturnUrl={relativeUri}"));
             var validateAbsoluteReturnUrlCalled = false;
 
-            Options.FromConfiguration.Notifications.ValidateAbsoluteReturnUrl =
+            var options = StubFactory.CreateOptions();
+            options.Notifications.ValidateAbsoluteReturnUrl =
                 (url) =>
                 {
                     validateAbsoluteReturnUrlCalled = true;
                     return true;
                 };
 
-            Action a = () => new SignInCommand().Run(httpRequest, Options.FromConfiguration);
+            Action a = () => new SignInCommand().Run(httpRequest, options);
 
             a.Should().NotThrow<InvalidOperationException>("the ReturnUrl is relative");
             validateAbsoluteReturnUrlCalled.Should().BeFalse("the ValidateAbsoluteReturnUrl notification should not have been called");