Add variable for a Date Only type of event and set it if the data is only a...

Add variable for a Date Only type of event and set it if the data is only a date. Use the modify() function of DateTime to add a day per iCal standards for an all day event.

Update the newEvent to check if we are only a date event and add the ['VALUE' => 'DATE'] per iCal standards to inform the system that this is a Date only event and should be treated as an All Day event.

Closes #3458229