Fixes BHV-17850

The change to fire IntegerPicker.onChange events whenever its value changed has complicated the date and time pickers orchestration of Date changes across pickers. Added a syncingPickers flag which is set before and unset after setChildPickers so that the onChange handlers for the IntegerPickers can immediately return if they're called in reaction to a value change initiated by the Date/Time Picker.

Also prevented child picker reflows when closing the pickers and fixed a bug where the day would change on a linked DatePicker when the hour of the linked TimePicker rolled over from 12am to 11pm (or vice versa).

*Note:* The original issue is due to setting the scrollTop of the hour picker which has been removed in this PR

Enyo-DCO-1.1-Signed-off-by: Ryan Duffy (ryan.duffy@lge.com)