SYSML2 — Optimize Pin mapping class generalization hierarchy

The separation of typed and untyped pin mapping classes leads to the same separation for each specialized mapping class for InputPin and OutputPin and for further specializations. This leads to many mapping classes and thus redundancies in the operations.

It can be simplified if the distinction of whether the pin has a type or not is not implemented via specialized mapping classes but within the rules.

Improve Pin mapping classes organization

The Pin mapping classes organization can be simplified by adding the distinction between typed and untyped pins in the ownedRelationship() operation instead of creating separate mapping classes.