By introducing this utility function, we ensure that any output value
is converted back to an ISO 8601 date and time string in UTC timezone.
Overall, it harmonize and factorize the way we output
values from date picker components.
Component was lacking some customization capabilities.
Using the browser calendar system wasn't enough modular.
This introduces a `locale` props, that allows a higher
customization of the component. By default, the calendar
system of the DatePicker is synchronized with the Cunningham
Provider.
