[EAK-517] Fix date parsing for coral-datepicker element

[mhoroshko]

Preconditions: example of dialog field where fetch doesn't work

    @Child(name = "../displayDate")
    @DialogField(
            name = "../displayDate",
            label = "Publication Date"
    )
    @DatePicker(
            displayedFormat = "MMMM DD, YYYY",
            type = DatePickerType.DATETIME
    )
    @DependsOn(query = "'../displayDate'", action = DependsOnActions.FETCH)
    private Calendar displayDate;

suggestion for fix:

(function ($, DependsOn) {
    'use strict';
    DependsOn.ElementAccessors.registerAccessor({
        selector: 'coral-datepicker', 
        set: function($el, value) {
             $el.prop('value', new Date(value));
        },
    });
})(Granite.$, Granite.DependsOnPlugin);