feat: AA-883 basic prototype for custom pacing pls in studio
refactor: merge with basic prototype for self paced courses from AA-844
feat: add due date estimate message in self paced courses studio modal
refactor: merge with main that has up to date self paced custom pls editor and tests
fix: only display projected date if start date exists
fix: tests to check grading date in outline
fix: only one warning message show at a time
fix: do not show projected date when it is before the start date
898684287a