LibJS: Introduce AbstractOperations.{cpp,h} and move various AOs there

Value.{cpp,h} has become a dumping ground, let's change that.

Things that are directly related to Values (e.g. bitwise/binary ops,
equality related functions) can remain, but everything else that's not a
Value or Object method and globally required (not just a static function
somewhere) is being moved.

Also convert to east-const while we're here.

I haven't touched IteratorOperations.{cpp,h}, it seems fine to still
have those separately.

Userland/Libraries/LibJS/CMakeLists.txt

@@ -22,6 +22,7 @@ set(SOURCES
     Lexer.cpp
     MarkupGenerator.cpp
     Parser.cpp
+    Runtime/AbstractOperations.cpp
     Runtime/AggregateError.cpp
     Runtime/AggregateErrorConstructor.cpp
     Runtime/AggregateErrorPrototype.cpp