oid2name: Add relation path to the information provided by -x/--extended

oid2name: Add relation path to the information provided by -x/--extended

This affects two command patterns, showing information about relations:
* oid2name -x -d DBNAME, applying to all relations on a database.
* oid2name -x -d DBNAME -t TABNAME [-t ..], applying to a subset of
defined relations on a database.

The relative path of a relation is added to the information provided,
using pg_relation_filepath().

Author: David Bidoc <dcbidoc@gmail.com>
Reviewed-by: Laurenz Albe <laurenz.albe@cybertec.at>
Reviewed-by: Guillaume Lelarge <guillaume.lelarge@dalibo.com>
Reviewed-by: Euler Taveira <euler@eulerto.com>
Reviewed-by: Mark Wong <markwkm@gmail.com>
Discussion: https://postgr.es/m/CABour1v2CU1wjjoM86wAFyezJQ3-+ncH43zY1f1uXeVojVN8Ow@mail.gmail.com