Generates an Ecto migration that installs the unit composite types and their aggregate functions into a PostgreSQL database.
The migration creates the cldr_unit and cldr_unit_with_usage
composite types and their sum, min, max and avg aggregates, so
that Localize.Unit.Ecto.Composite.Type columns can be summed and
averaged in the database. See Localize.Unit.DDL.
mix localize.unit.gen.migration -r MyApp.RepoOptions
-r,--repois the repository to generate the migration for, asMix.Ectoaccepts it. The default is the application's configured repository.