Allow use of rake db tasks

[#46224565]

The following rake tasks are added and work similar to how they work in
rails apps:
* db:create
* db:drop
* db:migrate
* db:migrate:status
* db:rollback
* db:schema:dump
* db:schema:load
* db:seed (but no db seeds defined at this time)
* db:setup
* db:version

The hidden task db:test:prepare is also available, which means `rake
spec` can depend on it so that the test database is dropped and
recreated from the development database when running specs (Although
there are yet to be database tests, this branch is in preparation for
that work that will be split between multiple developers.)