Initialization of omitted orientation (heading, pitch, roll) values at the position level is problematic

Describe the bug

Currently OpenSCENARIO initialized the orientation of a Position with 0s if it is omitted in the XML. This is a very problematic default since it becomes impossible to communicate to an action that it shall select its own sensible default for the omitted heading value. Therefore, the definition of the defaults shall generally be moved up to the Position "consumer level" as has been done as an exception in #506 (closed).

Describe the expected behavior

It shall be possible to specify default which make sense considering the semantics of the actions when positions are given without orientation.

Additional context

To avoid breaking compatibility it will probably be necessary to add many times to the UML model that the values will be default initialized with 0 for certain actions.