LibJS+js: Move the value print implementation to LibJS

And make it capable of printing to any Core::Stream.
This is useful on its own and can be used in a number of places, so move
it out and make it available as JS::print().

Userland/Libraries/LibJS/CMakeLists.txt

@@ -32,6 +32,7 @@ set(SOURCES
     Module.cpp
     Parser.cpp
     ParserError.cpp
+    Print.cpp
     Runtime/AbstractOperations.cpp
     Runtime/AggregateError.cpp
     Runtime/AggregateErrorConstructor.cpp