remove deprecated stringcase dependency

[leslievandemark]

Description of change

removes the stringcase library and replaces used functions.

Manual QA steps

• ran the tap locally.

Risks

• The stringcase pascalcase function is buggy for some edge cases. We opted to create a new implementation to transform strings into pascalcase. Where pascalcase function is used in the code, it is always transforming a snakecase stream name into a pascalcase stream name. If a stream name changed to something weird, the old implementation in stringcase might have transformed it differently than the new one. However, the stream names are hard coded so I don't see this being an issue.

Rollback steps

• revert this branch

AI generated code

https://internal.qlik.dev/general/ways-of-working/code-reviews/#guidelines-for-ai-generated-code

• this PR has been written with the help of GitHub Copilot or another generative AI tool

[luandy64]

Two passes over string seems a little wasteful.

If you add a new function to do the word splitting, then you can reuse it in snakecase and pascalcase.

def make_words(string):
    pass

def snakecase(string):
    return "_".join(word.lower() for word in make_words(string))

def pascalcase(string):
    return "".join(word.title() for word in make_words(string))

[leslievandemark]

I was trying to keep all the functionality of the old library, which gets a little tricky with one pass over splitting. However, the use case in the tap is only for CamelCase hardcoded stream names to snake_case and back. I'll update the function to something simpler that fits that case.