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/object-define-properties.js

@@ -174,7 +174,6 @@ assert (obj.a === "b");
 assert (obj.bar === 42);
 assert (obj.a === undefined);
 
-// This code should throw TypeError
 var obj = {};
 var props = {
   prop1: {
@@ -196,9 +195,15 @@ var props = {
   }
 };
 
-try {
-  Object.defineProperties(obj, props);
-  assert (false);
-} catch (e) {
-  assert (e instanceof TypeError);
-}
+Object.defineProperties(obj, props);
+var bar_desc = Object.getOwnPropertyDescriptor(obj, 'bar');
+assert(bar_desc.value === 2);
+assert(bar_desc.writable === true);
+assert(obj.prop2 === undefined);
+
+var prop1_desc = Object.getOwnPropertyDescriptor(obj, 'prop1');
+var prop3_desc = Object.getOwnPropertyDescriptor(obj, 'prop3');
+assert(prop1_desc.value === 1);
+assert(prop1_desc.writable === true);
+assert(prop3_desc.value === 4);
+assert(prop3_desc.writable === true);