Rework Object's [[OwnPropertyKeys]] (#4001)

I've removed the ecma_op_object_get_property_names method, and implemented the following ones:
- ecma_op_object_own_property_keys: this is now the internal [[OwnPropertyKeys]] method
- ecma_op_object_enumerate: this is used for the for-in iterator
- ecma_object_sort_property_names: this is used for sorting the property names of an object
- ecma_object_list_lazy_property_names: this is for getting the lazy instantiated properties
- ecma_object_prop_name_is_duplicated: this is for checking if a given property is duplicated in an object

Also the for-in operation with Proxy object works with this patch, #3992 should be closed

JerryScript-DCO-1.0-Signed-off-by: Adam Szilagyi aszilagy@inf.u-szeged.hu

tests/jerry/es.next/function-properties.js

@@ -39,7 +39,7 @@ assert(getProperties(func) == "dummy");
 
 var bound_func = (function() {}).bind(null);
 Object.setPrototypeOf(bound_func, prototype_obj);
-assert(getProperties(bound_func) == "dummy prototype");
+assert(getProperties(bound_func) == "dummy caller arguments prototype");
 
 // 'print' is an external function
 Object.setPrototypeOf(print, prototype_obj);