LibJS: Consolidate error messages into ErrorTypes.h

Now, exceptions can be thrown with
interpreter.throw_exception<T>(ErrorType:TYPE, "format", "args",
"here").

Libraries/LibJS/Tests/Proxy.handler-preventExtensions.js

@@ -30,7 +30,7 @@ try {
         Object.preventExtensions(p);
     }, {
         error: TypeError,
-        message: "Proxy preventExtensions handler returned false",
+        message: "Object's [[PreventExtensions]] method returned false",
     });
 
     o = {};