Write CI action to Check that `json-schema-files` and actual C# code are in sync

[hf-kklein]

We need a check, that the files in json-schema-files are in sync with the actual c# code base managed in this repository. We don't want to do manual re-generations like in #414 .
This is relevant to have our .ts package in sync: https://github.com/Hochfrequenz/bo4e-dotnet-ts-models (as of today this sync happens more or less manually: some one updates the json schemas, this triggers an update of the .ts package).

See e.g. the bo4e-python tooling (ask @lord-haffi), where the comparison happens.

The comparison shhuld be semantic, not string based.

Therefore:

• understand the test

  BO4E-dotnet/BO4ETestProject/TestJsonSchemaGeneration.cs

  Line 46 in 1c67c18

  public void TestJSchemaFileGenerationBo(int offset)

• encapsulate the logic from the test so far, that it can be run from the CI
• build a github action that checks the consistency