consul: migrate formula to casks

[botantony]

• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing HOMEBREW_NO_INSTALL_FROM_API=1 brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

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see Homebrew/homebrew-cask/pull/200992

[SMillerDev]

It really should be disabled first

[MikeMcQuaid]

Please disable this first, thanks!

[botantony]

the fact that this formula was initially migrated from casks complicates things a bit, maybe i should first remove "consul": "homebrew/core", from tap_migrations.json in cask repo and then do the migration 🤔

[MikeMcQuaid]

@botantony Please disable this before rerequesting review.

[botantony]

the formula was disabled yesterday (#208102)

[MikeMcQuaid]

@botantony Thanks! Please rebase this pull-request. Happy to merge just the tap_migrations.json change for now and consul.rb changes shouldn't be needed.

[botantony]

I just tested things locally and brew audit --except=installed --tap=homebrew/core cannot find consul dependency for disabled envconsul formula (hmm... maybe I should submit formulae removal first)