convert CSV to JSON at runtime

[musoke]

Currently, https://github.com/OpenBeta/sandbag/blob/f3e46f8d6855a614cdf59138d0b9d9829f9efcca/src/data/csvtojson.ts is used during development to convert CSV files of grade tables to JSON. I think this should happen at run time instead. This would have benefits including

• fewer steps for developers
• fixes https://github.com/OpenBeta/sandbag/issues/120
• fewer irrelevant lines in diffs
• sandbag could use user-defined tables, possibly even linking a sheet in the "cloud". (This would be low priority.) The CSVs included with sandbag would remain as the canonical conversion tables.

Possible issues

• Latency. Should check with https://github.com/openBeta/open-tacos and https://github.com/OpenBeta/openbeta-graphql/.