Change DD4hep Attribute handling

Using hasAttr(const XmlChar* att) has proven to be too fragile (as XmlChar is typedefed and can be machine and external dependent).

Change the ActsExtension to ProtoMaterial with a different translation schema. Instead of

<layer_material representing="true" inner="true" outer="false"/>

this will change to

<layer_material surfaces="representing, inner">

etc.