LibJS+LibUnicode: Separate number formatting methods from Locale.h

Currently, we generate separate data files for locale and number format
related tables/methods, but provide public accessors for all of the data
in one Locale.h file. Rather than continuing this trend for date-time,
relative time, etc. formatting, it's a bit easier to reason about if the
public accessors are also in separate files.

Userland/Libraries/LibUnicode/CMakeLists.txt

@@ -5,6 +5,7 @@ SET(SOURCES
     CharacterTypes.cpp
     CurrencyCode.cpp
     Locale.cpp
+    NumberFormat.cpp
 )
 
 serenity_lib(LibUnicode unicode)