Remove abstract Class HasKind and incorporate directly in class Subclass

[BirgitBoss]

Is your feature request related to a problem? Please describe.
The only class inherting HasKind is Submodel (in former versions it was also SubmodelElement). Abstract classes are typically only introduced if several classes are inheriting from them.

Describe the solution you'd like
Remove abstract Class HasKind and incorporate directly in class Submodel

The change is backward compatible but changes the schemas implementing the abstract classes as well.

Some constraints are effected like Constraint AASd-119: If any Qualifier/kind value of a Qualifiable/qualifier is equal to 980 TemplateQualifier and the qualified element inherits from "hasKind" then the qualified element 981 shall be of kind Template (HasKind/kind = "Template").