Scaffolds a step in the current project's cookbook, with every facet stubbed out, and a test for it.
mix composer.gen.step tailwind_plugins
mix composer.gen.step ash/postgreswrites lib/composer/<app>/steps/ash/postgres.ex (module
Composer.<App>.Steps.Ash.Postgres) and
test/composer/<app>/steps/ash/postgres_test.exs.
A step's templates go in the directory named after its file with a
leading underscore (lib/composer/<app>/steps/ash/_postgres/), and template/1 refers to
them by a path relative to it. The directory is not created; add it when
the step needs a template.
Group related steps with /: ash/postgres and ash/sqlite read better,
and list together, than ash_postgres and ash_sqlite. Use a flat name
for a step that stands alone.
If the cookbook module is guarded for bundling (see
mix composer.gen.cookbook --bundled), the step and its test get the same
guard.