RSRP-441357: Run test in this and all derived test fixtures

If I have a complex test hierarchy like this:

[TestFixture]
class A {
    [Test] public void Test001() { DoTest(); }
    [Test] public void Test002() { DoTest(); }
    //...
    [Test] public void Test999() { DoTest(); }
}

class B extends A {
}

class C extends A {
}

abstract class D extends A {
}

class F extends D {
}

class G extends D {
}

(see our HtmlHighlightingTest for an example)

It would be really nice if I could run, for example, Test567, in class A and all derived fixtures.
Currently what I do is manually adding all derived classes and manually deleting all tests except Test567 in each of them. Boring.