fix(brew search): Improve hints for apps migrated within the same tap

[yermulnik]

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Since the #21224 was merged and released via https://github.com/Homebrew/brew/releases/tag/5.0.6, the tap migrations within the same tap are working for the third-party taps. However the same wasn't implemented for brew search which still outputs odd hints for such apps that were migrated from a formula to a cask within the same tap. E.g.:

> brew search tfswitch
[…]
==> Casks
yermulnik/tfswitch-homebrew-tap/tfswitch

If you meant "tfswitch" specifically:
It was migrated from yermulnik/tfswitch-homebrew-tap to tfswitch.
You can access it again by running:
  brew tap tfswitch/
And then you can install it by running:
  brew install tfswitch

This is a follow up to #21207 and attempts to provide a more meaningful and correct hints for apps migrated within the same tap.

Cc @MikeMcQuaid

[Copilot]

Pull request overview

This PR updates Homebrew’s missing-formula hinting to produce more accurate guidance when a formula has been migrated to a cask within the same tap, improving the brew search/missing formula messaging for third-party taps using tap_migrations.json.

Changes:

• Add a “same tap” migration path that changes the message and avoids suggesting brew tap … when the migration stays within the same tap.
• Adjust the suggested install command to use brew install --cask for same-tap formula→cask migrations.
• Simplify/reshape the output formatting to better fit the new messaging.

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[MikeMcQuaid]

Thanks for the PR @yermulnik! This logic all looks good and makes sense to me and the wording improvements are 😍.

Just requesting @cho-m give it another look as I'm always a bit twitchy about this sort of logic.

[cho-m]

I'm fine with changes.

There are some scenarios that may not be handled ideally, but that also holds for original code so those could be improved later on. For example, it should be possible to do the reverse (cask-to-formula migration). Also I think we do support { "<name>": "<tap-name>" } as an alternative to perform same migration.

DRY-ing the code would help as we duplicate the handling of this in multiple locations.