array_concat does not work with nested empty arrays

[izveigor]

Describe the bug

The user @parkma99 first implemented the mechanism of operation of the function array_concat with empty arrays. But current implementation does not support nested empty arrays.

To Reproduce

❯ select array_concat(make_array(make_array(1, 2), make_array(3, 4)), make_array(make_array()));
+----------------------------------------------------------------------------------------------------------------+
| array_concat(make_array(make_array(Int64(1),Int64(2)),make_array(Int64(3),Int64(4))),make_array(make_array())) |
+----------------------------------------------------------------------------------------------------------------+
| [[1, 2], [3, 4], []]                                                                                           |
+----------------------------------------------------------------------------------------------------------------+

Expected behavior

❯ select array_concat(make_array(make_array(1, 2), make_array(3, 4)), make_array(make_array()));
+----------------------------------------------------------------------------------------------------------------+
| array_concat(make_array(make_array(Int64(1),Int64(2)),make_array(Int64(3),Int64(4))),make_array(make_array())) |
+----------------------------------------------------------------------------------------------------------------+
| [[1, 2], [3, 4]]                                                                                               |
+----------------------------------------------------------------------------------------------------------------+

The output should be similar to PostgreSQL.
PostgreSQL:

postgres=# select array_cat(array[array[1, 2], array[3, 4]], array[array[]::integer[], array[]::integer[], array[]::integer[]]);
   array_cat   
---------------
 {{1,2},{3,4}}
(1 row)

Additional context

No response