This is an improvement (in my opinion) to the `brews` command that prints each leaf formula (in white), followed by its dependencies (in blue), on each line. Compared to the existing flat list of formulae, the new layout is both more compact and more informative, by differentiating leaves from dependencies at a glance.

Screenshot:
<img width="530" src="https://user-images.githubusercontent.com/1753319/130641713-b78535c9-e3f5-4dbb-80f8-22bc00e1129d.png">