Feature Request: Expose Cabal components in ls dependencies json

[aherrmann]

Feature Request

I would like the output of stack ls dependencies json to contain the Cabal components of a package, e.g. lib, exe:xyz.

Motivation

The upcoming release of stack contains the new stack ls dependencies json feature which returns the package dependency graph and some additional package metadata for a given project (package names, versions, locations, dependencies) in a JSON format. This is very useful for build tools that would like to call out to stack to determine how to build Stackage dependencies. However, some packages contain executable components that other packages depend on, or don't contain library components at all, e.g. alex. At present it is difficult to determine which components a package provides. The motivating use-case is Bazel with rules_haskell, see tweag/rules_haskell#1306.

This feature request is similar to #5274, however it seemed sufficiently independent to warrant its own issue.