feat: expose casks in tap.to_hash for tap-info --json

[forivall]

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Hey yall. I wanted to install [meme] all the fonts [/meme] from homebrew-cask-fonts (well, i really want to generate specimens for all of them so i can find a font that looks like the ✨ aesthetic ✨ i'm looking for, but that's a larger change and my ruby experience is minimal), and so i wanted to see all of the casks it provides, and adding it to the hash seems like the correct place, as formula_files and command_files are there.

With this, I was able to complete my task with brew tap-info homebrew/homebrew-cask-fonts --json|jq -r '.[] | .cask_files[]' | sed -e 's|.*/||' -e 's/\.rb$//' | xargs brew cask install.

[forivall]

and as far as tests go, a lot of unrelated tests were failing, and it looks like the only test for to_hash is not something that would fail. https://github.com/Homebrew/brew/blob/a915114/Library/Homebrew/test/tap_spec.rb#L141 . Let me know if there's anything that needs to be done for that.

[MikeMcQuaid]

Thanks for the PR! Seems reasonable to be but interested in @EricFromCanada and @reitermarkus' thoughts.

[EricFromCanada]

Since a list of formula_names is defined, I think cask_tokens should be provided as well.

[MikeMcQuaid]

Thanks so much for your contribution! Without people like you submitting PRs we couldn't run this project. You rock, @forivall!