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/Symbol.for.js

@@ -21,7 +21,7 @@ try {
         Symbol.for(Symbol());
     }, {
         error: TypeError,
-        message: "Can't convert symbol to string",
+        message: "Cannot convert symbol to string",
     });
 
     console.log("PASS");