Complete DSL input

[turekj]

The PR ships completely parsed DangerDSLJSONType structure from the JSON schema.

Unfortunately, I was unable to parse the schema with any code-generation tool for Python (it failed either on missing top-level definition, circular references or some validation error due to the types). So I decided to roll my own generation code for the sake of the project. It does a couple of cool things:

• it provides full type hints on the structure
• it patches some reserved Python keywords in the structure (like from or self),
• it fixes all the casing in the JSON schema (it handles snake-case modified_files, camel-case updatedDate and camel-case with shortcuts thisPR
• it builds nested objects outside of the regular schema definitions

Since this part of the code relies on Jinja templates, it can be potentially reused for other projects, too 👍

EDIT: The PR is huge because it ships the schema with the project and also the generated model file, sorry 🙇

[turekj]

Thanks for the review @orta 🙇 Seems like we're getting closer to the initial release 🔥