Clarify enrollment end date vs. sale date, or make it date + time

**Is your feature request related to a problem? Please describe.**
Enrollment End Date is for the beginning of the selected day. Sale end date (for an access plan) is until the end of the day. This causes confusion on when the sale or enrollment ends.

**Describe the solution you'd like**
Add a label making it explicit, or switch to date + time. Make the time match the current behaviour, ie. end of day for sale end date (23:59:59) and beginning of day (00:00:00) for enrollment end date so there's no change in behaviour for existing sites.