Add command line command to create course in either split or mongo

PLAT-189

@explorerleslie this allows devops to create courses in split via command line
@doctoryes @cahrens please review
In what sense does this test a course migration? Doesn't it just create a course in Mongo and then again in Split?

Also, if the first Mongo course created wasn't cleaned up between tests, the second Split course creation would fail, correct? Is there a test for that course_id collision across modulestores elsewhere?