Add autodeclaring constructor signature to DataObjectHandle

it allows declaration and initialization of DataObjectHandle data members in
headers (as for Gaudi::Property).

To simplify declaration of read or write handles, two helper classes have been
added:
- DataObjectReadHandle
- DataObjectWriteHandle

For example
```cpp
class MyAlg: public Algorithm {
  using Algorithm::Algorithm;
  DataObjectReadHandle<Tracks> m_tracks{this, "TracksLocation",
                                        "/Event/Rec/Tracks"};
  DataObjectWriteHandle<Vertices> m_vertices{this, "VerticesLocation",
                                             "/Event/Rec/Vertices"};
};
```