Format student data into student-level records

Currently, the data is in student-by-year-level records. One helpful alternate format for some analysis is pure student-level format, where all time-varying fields (e.g. test scores, GPA, attendance) are represented in multiple columns, e.g. with each field suffixed by school year.

Start by locating the transformation that currently represents data as student-by-year-level records; no file, test, or entry point is named in the issue. Done means producing one record per student, with time-varying fields such as test scores, GPA, and attendance represented in columns suffixed by school year.

Written by the indexing model from the issue text.