[INTERNAL][FIX] sap.m.DatePicker, sap.ui.unified.Calendar

-Fixes in DatePicker and Calendar
-Added CalendarLegend HCB styles
-Modified CalendarSpecialDays sample

Change-Id: I80c360b72e805bf5769b787f2d4a8e6695fa4884
Merge "[INTERNAL][FIX] sap.m.DatePicker, sap.ui.unified.Calendar"