LibUnicode: Use BCP 47 data to filter valid calendar names

Author: https://github.com/trflynn89
Commit: 70ede2825e
Pull-request: https://github.com/SerenityOS/serenity/pull/12558

Userland/Libraries/LibUnicode/DateTimeFormat.cpp

@@ -91,7 +91,6 @@ StringView calendar_pattern_style_to_string(CalendarPatternStyle style)
     }
 }
 
-Optional<Calendar> __attribute__((weak)) calendar_from_string(StringView) { return {}; }
 Optional<HourCycleRegion> __attribute__((weak)) hour_cycle_region_from_string(StringView) { return {}; }
 Vector<HourCycle> __attribute__((weak)) get_regional_hour_cycles(StringView) { return {}; }