Refactor of cpg-language-python

[maximiliankaul]

This PR aims at minimizing Python code in favor of Kotlin code in our CPG. This will benefit the overall experience as

• the code will be easier to maintain (debugging, similarity to other frontends, ...)
• we can get rid of a lot of file handling background magic

This goal is achieved in a similar manner as with the other frontends (i.e. cpg-language-go). We will still use Python's ast module to parse Python code but then map all Python objects to a Kotlin interface. All logic will be implemented in Kotlin.

Open todos:

• make everything work as good as before (or better ;))
• update README
• fix the PythonLanguageFrontend functions (getCode(), ...) -> need to store the file name somewhere
• remove all pycodestyle references (github runner, ...)
• remove spotless checks for Python files (as there will be no more Python files) @oxisto

[oxisto]

I did a first cleanup pass on this. I removed everything which was breaking things in other language frontends. I also added initial type parsing and some type inference work, which we sill can improve later on, but it works for the tests.

[sonarqubecloud]

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62.8% Coverage
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