AddParameter and target-typed new

[jcouv]

Adding an argument to an implicit object creation doesn't trigger AddParameter.

Similarly, GenerateConstructor doesn't trigger on C c = new(1, 2, 3, 4); to offer to add a constructor with 4 parameters.

class C
{
    C(int i) { }
    void M()
    {
       C c = new(1 $$); // typing a second argument here should trigger AddParameter
    }
}

Relates to #28489 (target-typed new feature)