First version of CodeI/O reasoning data (#264)

* notebook for prepping first set of raw code files
* updated codeio processing notebook for repo-level processing
* fix for edge case in codeio scoring
* Add reformat notebook
* filtering pass
* add non-determinism filtering
* Tweak CodeIODataset & include first real data
* add basic codeio test, metadata

notebooks/codeio/.gitignore

@@ -1 +1,2 @@
 raw_files/
+output/