RSRP-199079: In Unit Test runner, show parent class names for nested TestFixture classes

It's sometimes nice to be able to organise unit tests like this:

namespace Tests.FooNamespace
{
public class FooTests
{
[TestFixture]
public class ACollectionOfFooTests
{
[Test]
public void TestSomething() { etc }
}

[TestFixture]
public class AnotherCollectionOfFooTests
{
[Test]
public void TestSomething() { etc }
}
}
}

It would be good if the Resharper unit test runner showed the parent class names of the nested classes. Currently it looks like this:

• Tests.FooNamespace
  

      - ACollectionOfFooTests
         - TestSomething
      - AnotherCollectionOfFooTests
         - TestSomething
  
  With the parent classes it would look like this:
  

  
  
  
• Tests.FooNamespace

- FooTests.ACollectionOfFooTests
- FooTests.AnotherCollectionOfFooTests
- TestSomething