Edc-visit-schedule

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- remove Onschedule model post-save signal. The signal was calling put_onschedule.
This was a redundant call since it was put_onschedule() that created
the OnSchedule model instance in the first place.
- Remove `resave` method on Schedule and SubjectSchedule. Replace with
Schedule.refresh_schedule which wraps SubjectSchedule.refresh_appointments.
SubjectSchedule.refresh_appointments now explicitly calls create_appointments.
That was the original intention of the now removed post_save signal.
- add a manager method to OnSchedule to call put_onschedule (mostly for
tests)..

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- add methods to `schedule` to list visits where CRFs and requisitions are required

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- requisition can now accept both panel and panel group
- add some utils to check if baseline

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- pass visit_schedule_name and schedule name to ``take_off_schedule`` when
calling appointment manager method to delete future appts