* Fix type mismatches in the course_modes migrations
* Fix type mismatches in the course_action_state migrations
* Fix type mismatches in the schedules migrations
* Fix type mismatches in grades migrations
* Fix type mismatches in video_pipeline
* Fix type mismatches in api_admin
* Fix mismatches in credential migrations
To allow the notify_credentials management command to run from a
jenkins job, we want to allow the command to pull its arguments
from the database, rather than the jenkins interface.
So this adds a table that admins can adjust in the DB and a new
argument for notify_credentials to tell it to go look there.
LEARNER-6196
LEARNER-6197
