TrackerEndcap_o2_v06 does not create a layer DetElement

[tmadlener]

The TrackerEndcap_o2_v06 (and almost certainly most of its predecessors) do not put the modules in each layer into a separate Assembly and a layer DetElement. The TrackerBarrel_o1_v05 on the other hand does just this. Having a layer DetElement would make it much more straight forward to walk the created geometry tree and would greatly facilitate the conversion of the DD4hep geometry to Acts, as currently being done on key4hep/k4ActsTracking#36

Is there a specific reason why the modules are placed directly into the Endcap DetElement rather than creating DetElements for each layer.

[andresailer]

I don't know if there is a reason for this lack of layer detelement.