Add currency, number and datetime settings to sample configuration
For service and UI consistency, we should have all locale-related settings in the system configuration file. Then services can load from the configuration, expose settings through an API, which the UI can also use.
All currency settings in settings-sample.env (code, symbol, symbol side, decimal places)
All number settings in settings-sample (grouping separator, size, decimal separator)
All datetime settings in settings-sample (date format, date time format)