[Feature]: Add Multi-File Solution Handling

Per notes on [PR#45](https://github.com/exercism/python-representer/pull/45), we should be handling multi-file student solutions. The change will need to be made across all the tooling, not just in the representer.

Some decisions on how this happens still need to be made, and we should look at tracks such as `Java`, `C#`, `C++`, and `C` to see how they are handling this scenario, and how the "final result" is displayed.