which-formula: port to Ruby and mark install status

[HaraldNordgren]

Fixes #22282.

Make which-formula show more useful info about a binary:

• Install markers for formulae
• PATH shadowing
• (Rewrote in Ruby to access helpers)

❯ brew which-formula clang
==> clang
llvm ✔
llvm@14 ✘
llvm@15 ✘
llvm@16 ✘
llvm@17 ✘
llvm@18 ✘
llvm@19 ✘
llvm@20 ✔
llvm@21 ✘
metashell ✘
Warning: clang is shadowed by /usr/bin/clang earlier in your PATH.

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Claud Code, Extra High

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[MikeMcQuaid]

Already open PR implementing this in #22300