cabal new-path

I find myself often needing paths for cabals new-build artifacts. stack has a `path` command, that allows to retrieve information about directories for the current setup.

A `cabal new-path` command providing similar functionality would be quite useful.

E.g.

`cabal new-path --dist-dir` would provide the directory that used to be `dist` for the current target. E.g. the one that `cabal new-build` would build by default.

This could of course be discriminated by target.

Start by reviewing how Stack's `path` command exposes build-artifact directories and how `cabal new-build` selects its default target. Define the supported `cabal new-path` options, including `--dist-dir` and target discrimination, then verify that each option reports the expected directory for the current setup.

Written by the indexing model from the issue text.