fix: pascal case

[Mokto]

First, thanks for your library, I'm REALLY happy to be able to remove the java dependency from our codebase!

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Motivation: the most popular golang openapi plugin, https://github.com/swaggo/swag, generates references in that format:

packagename.myFunction.

This library then generates types with the name: packagename_myFunction.

My PR is addressing that issue and would generate PackagenameMyFunction

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1. Any typescript interface should be written in pascal case, in my opinion.
2. The java library was already changing those types into pascal case.

Note: this change is really major and should be considered as a breaking change. I can potentially add a new parameter to the command line tool to be compatible with the previous versions.

[ferdikoomen]

@Mokto We should definitely have a flag for this, since its a breaking change. Would you be able to add this? Ideally we could have a flag called --case, with options for pascal, snake, etc.?

Also check this PR: #1465

[ferdikoomen]

@Mokto Closing this PR since there has been no acitivity