Cldr Dates Times version 2.19.2

Bug Fixes

• Reinstate Cldr.DateTime.Format.date_formats/3 which was incorrectly removed in version 2.19. Version 2.19 made efforts to improve the symmetry of Cldr.Date, Cldr.Time and Cldr.DateTime. Part of that work is to have each of those modules contain the functions formats/3 and available_formats/3. It was not intended at this time that the equivalent functions be removed from Cldr.DateTime.Format. Thanks to @tjchambers for the report. Closes #51.