Add "Leaves"

[fry69]

Before submitting

• I have searched the issues and pull requests for duplicates.
• I am proposing a specific improvement to BrewUI with a use case and a clear outcome.

Problem and use case

The CLI offers to show "leaves":

$ brew leaves --help
Usage: brew leaves [--installed-on-request] [--installed-as-dependency]

List installed formulae that are not dependencies of another installed formula
or cask.

  -r, --installed-on-request       Only list leaves that were manually
                                   installed.
  -p, --installed-as-dependency    Only list leaves that were installed as
                                   dependencies.
  -d, --debug                      Display any debugging information.
  -q, --quiet                      Make some output more quiet.
  -v, --verbose                    Make some output more verbose.
  -h, --help                       Show this message.

The Homebrew GUI should also offer this view.

Proposed behaviour

TBD?

Probably best to offer a toggle/switch/button in the "Installed"/"Your packages" view, above the list?

There is the danger of cluttering the interface, but I think this is a worthwhile feature to have.

Alternatives considered

• Visually (via color?) separate packages that are dependencies for other packages.
• Leave it as is.

This is a quality of life feature, not a bug.

macOS and Homebrew context

No response

[MikeMcQuaid]

We shouldn't add leaves but should offer "installed on request".