Feature Request: Allow picking the first possible target if and only if target selector is ambiguous

Sometimes it is convenient to select a target if the given selector is ambiguous, either based on the component type or just the first that is accessible.

This is specifically helpful as cabal supports Filepath targets. Given a Filepath target, cabal figures out the component the filepath belongs to and loads that. However, sometimes a Filepath is part of multiple components. In that case, the target is ambiguous and no build-info is printed.
Especially for tooling, it would be better if you defaulted to just *some* component, as the options probably don't differ too much, and we keep working most of the time.

We propose here to add `--pick-first-target` to `NixStyleFlags`, so that users can conveniently decide to just pick a target and not error if the targets are ambiguous.

PR is here: #7482

Edit: Added better motivation