Fixes #18849 : fix duplicate casks when symlinks exist

[vidishanevatia]

When a cask is renamed (e.g. logi-options-plus to logi-options+), Homebrew creates a symlink in the Caskroom directory. Currently, brew list --cask shows both the original and symlinked cask as separate entries. This patch modifies the listing logic to resolve symlinks and show only unique casks.

Fixes #18849

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[MikeMcQuaid]

Thanks so much for your first contribution! Without people like you submitting PRs we couldn't run this project. You rock, @vidishanevatia!