Support to returning a predicate

[arialdomartini]

Honestly, I would love if TUnit supported returning a predicate. This would open the door to supporting Property-Based Testing:

[Test]
public bool MyTest()
{
    var number = MySut();
        
    return number == 42;
}

The reason why xUnit's has separate Fact and Theory is really because of that: Theories are supposed to only assert via predicates. Libraries such as FsCheck allow this style:

[Property]
bool my_test(int n) =>
     MySut(n) == 42;