Extend psql's \lo_list/\dl to be able to print large objects' ACLs.

Extend psql's \lo_list/\dl to be able to print large objects' ACLs.

The ACL is printed when you add + to the command, similarly to
various other psql backslash commands.

Along the way, move the code for this into describe.c,
where it is a better fit (and can share some code).

Pavel Luzanov, reviewed by Georgios Kokolatos

Discussion: https://postgr.es/m/6d722115-6297-bc53-bb7f-5f150e765299@postgrespro.ru