ApplicationVertex set max_atoms_per_dimension_per_core during init

[Christian-B]

it would be good to set max_atoms_per_dimension_per_core
including using the default atom_shape
this remove the optional
And therefor also trigger then new check

But to do this several tests will need to be changed to use SimpleTestVertex(
as max_atoms_per_dimension_per_core defaults to atom shape which needs an n_atoms

[Christian-B]

The issue is that to do this check during init requires other params to be available which means changing many application vertices