cask_reason will suggest brew cask uninstall

[zachauten]

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Closes #6260

[zachauten]

Still a work in progress, just opening the pull request to get some suggestions. @MikeMcQuaid I know you mentioned not wanting to use Homebrew.args in #6247, would you mind explaining the reasoning behind that?

I'm using it here temporarily out of convenience because this PR introduces a second conditional that depends on the command brew was called with (brew uninstall uses Cask::Caskroom.casks while brew install & brew info use Cask::CaskLoader.load)

[MikeMcQuaid]

@MikeMcQuaid I know you mentioned not wanting to use Homebrew.args in #6247, would you mind explaining the reasoning behind that?

It's global state that's better passed explicitly to the class rather than handled implicitly like this. That will make it easier to test and refactor in future.

[MikeMcQuaid]

Looks great, thanks again @zachauten!