remove remaining typing errors

[danieleades]

tracking issue for addressing the remaining type errors

• shrink mypy whitelist for 'environment' module #2056
• shrink mypy whitelist for 'extensions' module #2055
• shrink mypy whitelist for 'main' module #2060
• 'prompt' module
• run mypy on tests directory #2059
• refactor cookiecutter.hooks.run_pre_prompt_hook

[danieleades]

@jensens what "shape"/type is the 'prompts' object in the code?

Is this a reasonable reference: https://cookiecutter.readthedocs.io/en/stable/advanced/human_readable_prompts.html?

Is the "prompts" key required for every nested dict?

that 'prompts' module is a horrible bit of code (insofar as typing is concerned), i think it's going to take someone with a lot more familiarity with the code base than I to get that ship shape and removed from the whitelist

[danieleades]

refactoring cookiecutter.hooks.run_pre_prompt_hook is also going to help, but it's difficult to track the non-local type errors a refactor introduces with so many modules whitelisted. Will revisit once all the open PRs are merged

[danieleades]

ping @jensens! There are several PRs ready to merge