Student Categories and User Dataframe joined on UW Net ID

[nick-falco]

When creating the RAD datafile the Student Categories metadata file dataframe is joined to the canvas-analtyics User model dataframe. This join uses the UW net id which is prone to change. This could lead to records potentially getting dropped.

See https://github.com/uw-it-aca/canvas-analytics/blob/main/data_aggregator/dao.py#L1159

We need to determine a way to join these dataframes that is not prone to data loss. Alternatively we could keep the Student Categories file more up to date.

[nick-falco]

UPDATE: The student categories file is now updated weekly. See PR #210