Extend homebrew badge to support 3rd-party taps

:clipboard: **Description**

As homebrew recommends more and more formulae to live in 3rd party taps, it would be necessary for these tapped formulae to have badges pointing to the 3rd-party tap.

Homebrew itself already has a format for installing from a 3rd party tap directly:

`brew install owner/tap/formula` would point to formula under: github.com/owner/homebrew-tap

As such, my request would be that the existing homebrew badge just accept formula names that include the `owner/tap/` prefix.

Locate the existing Homebrew badge implementation and its tests, then read how formula names are parsed and mapped to installation links. Extend the accepted input to include the owner/tap/formula form and verify that the resulting badge points to the corresponding third-party tap.

Written by the indexing model from the issue text.