feat: Include pubspec_overrides.yaml into the bundle

**Description**

Allow bundling a brick with a hook that has dependency overrides inside a `pubspec_overrides.yaml`.
Currently the bundled version will only include `pre_gen.dart`, `post_gen.dart` files and a `pubspec.yaml`.

**Additional Context**

This is useful when managing multiple bricks with shared hooks using [melos](https://pub.dev/packages/melos)