Support for existing react-native dependencies CLI command

Few days ago, I released [react-native-shared-code](https://github.com/fdnhkj/react-native-shared-code), a tool that calculates the percentage of
* shared code across platforms
* platform specific code

It uses React Native packager and takes as input the result of `react-native dependencies` CLI command.
Now, I would like to investigate the integration of this tool with RN projects using `haul`.
That's the reason why I would like `haul` to support `react-native dependencies`.

Find below my comment on issue https://github.com/fdnhkj/react-native-shared-code/issues/1

> This project needs the list of bundle dependencies as input to calculate the share code percentage.
> So Haul would need to provide that list given an entry point and a platform.
>
> For reference, for React Native packager, I used `react-native dependencies` CLI command (see [index.js#L15](https://github.com/fdnhkj/react-native-shared-code/blob/master/index.js#L15)). You can find the command implementation [here](https://github.com/facebook/react-native/blob/master/local-cli/dependencies/dependencies.js).
>
> Let me know if I can help!

Start by reading the referenced React Native dependencies command implementation and the react-native-shared-code example to understand the required entry point and platform inputs. Then locate Haul's CLI command handling and determine how completion should expose the bundle dependency list for those inputs.

Written by the indexing model from the issue text.