[Blueprint Courses] Automatically Adjust Dates When Copying a Blueprint

[HParkhurst]

If we have a blueprint shell for a course that has multiple cohorts starting on different dates, eg. some on April 5th, others on April 8th, we should be able to adjust the dates before copying out the shell.

Functionality would be the same as when you copy out a whole course, asking to adjust dates, choosing new dates and mapping it out on the new copy/blueprint shell.