Add font-casker tool back

[Aaron-212]

This PR is not a request for addition of Cask.
In the original Homebrew/homebrew-cask-fonts there is the font-casker tool, but after the migration the tool has been removed. I find it quite useful, so I'd like to add it back.

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[bevanjkay]

Yeah I think this is ok to move over, but is relevant to #174192

[Aaron-212]

Yeah I think this is ok to move over, but is relevant to #174192

Great, I'll just close this PR then.