Add RedirectToAction assertions with lambda expression to specify controller action

Syntax would look like this:

``` C#
var result = controller.Action(model);

result.Should().BeRedirectToActionResult(x => x.AnotherMethod());
```

No files or tests are named. Start by locating the existing BeRedirectToActionResult assertions and compare their current action-selection API with the lambda syntax shown in the issue. Done means the generic assertion accepts a lambda such as x => x.AnotherMethod() and has coverage for that usage.

Written by the indexing model from the issue text.