Fix an RRULE issue with all-day events expanded by BYHOUR or high-frequency RRULES

Summary:
Ref T10747. If you have an all-day event, we normally return all-day events.

If the frequency is HOURLY or higher though, or the set has been expanded by a rule like BYHOUR, we need to iterate hours/minutes/seconds and return date-time results.

Test Plan: Unit tests now pass.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10747

Differential Revision: https://secure.phabricator.com/D16612