[Task] Asset Administration Shell - describe semantics of Entity submodel element

[BirgitBoss]

Is your task related to a problem? Please describe.
BAMM shall support the semantic definition of entity submodel elements in the Asset Administration Shell (AAS). Entity submodel elements represents a thing that may have an assetId or that may be represented by a digital twin itself

Describe the solution you'd like
Introduce a predefined abstract entity with name "Part" and the defined attributes of AAS Entity Element.

Describe alternatives you've considered
introduce a new namespace for AAS because Entity is a little bit AAS specific in contrast to the other submodel elements.

Additional context
see also #138 (reference element)
https://industrialdigitaltwin.org/wp-content/uploads/2021/09/07_details_of_the_asset_administration_shell_part1_v3_en_2020.pdf