Better error message when passing in unknown scene

[mattdeitke]

There is currently a pretty ugly error message on main when an unknown scene in passed in:

The error message occurs because we try to sort by the pattern re.search(r"FloorPlan[_]?([a-zA-Z\-]*)([0-9]+)_?([0-9]+)?.*$", scene_name). But, not all scenes in the main build work with the pattern anymore. For instance, trying it with FloorPlan_ExpRoom results in None, which then results in the AttributeError: 'NoneType' object has no attribute 'group'.

This PR just calls sorted() instead of trying to sort by key_sort_func. The downside is that it may be a little less natural, where FloorPlan10 might come before FloorPlan1, but it's much more robust to new scene names in the build.

Full notebook: https://colab.research.google.com/drive/1207Px1enUPqzJ2mTIkvrc-OA7eygpEyT?usp=sharing