Harmonize casing with published JSON and XML schemas

[mristin]

We used a hard-coded list of abbreviations in aas-core-codegen for generating the schemas. As we updated the meta-model, we mistakenly forgot to update this list. This resulted in incorrect casing in the schemas (for example, IEC is correctly cased, but Aas and Xsd not).

This separate list must be removed, as it is almost certain that we will forget to update it in the future as well.

Here is a suggested fix:

• We will therefore harmonize the casings in the meta-models with the published schemas (even though they are incorrect).
• Additional tests in this repository should enforce the coorectness of the casing for the future meta-models.
• aas-core-codegen should dispose of any hard-coded lists, and rely on the casing as-is in the meta-model.

[mristin]

Fixed in https://github.com/aas-core-works/aas-core-codegen/tree/mristin/Change-JSON-naming-for-V3.

This version of aas-core-codegen is now used to generated JSON schema, XSD and RDF+SHACL.

The first relevant commit is: https://github.com/aas-core-works/aas-core-codegen/commit/57c08492fe4f7c8c92a33f374483681d07be3916