Create database migration tests with fake data

[maxachis]

Currently, we don't have a way to automate comprehensive testing of database migrations.

We have targeted database migration tests, which add a small amount of sample data on areas expected to be impacted by a given migration, but there is always the possibility for unexpected errors to crop up elsewhere.

A way to be more comprehensive is to ensure that data is populated which contains a wider range of permutations for database values -- most notably, having all tables contain at least some data, and tables with enums having rows containing all combinations of enums, which are most likely to be impacted by a migration.

This is an issue of indeterminate importance; it may well be that our current methods are sufficient, and we don't need to go beyond that.