[Feature]: Add Multi-File Solution Handling

[BethanyG]

Per notes on PR#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.