Make DateTime option configurable

Currently, the UiSchema generated for the DateTime picker is initialized with fixed configuration options.
By default, the @DateTime annotation is automatically added when an @Option member is a date type (ie LocalTime, ZonedDateTime, etc.) but no configuration is allowed.
Thus, the

• date format is always set to "YYYY/MM/DD"
• time are always using seconds
• UTC is always used.

The goal of this issue is to allow a date configuration more accurately.