psql: Improve psql tab completion for GRANT/REVOKE on large objects.

psql: Improve psql tab completion for GRANT/REVOKE on large objects.

This commit enhances psql's tab completion to support TO/FROM
after "GRANT/REVOKE ... ON LARGE OBJECT ...". Additionally,
since "ALTER DEFAULT PRIVILEGES" now supports large objects,
tab completion is also updated for "GRANT/REVOKE ... ON LARGE OBJECTS"
with TO/FROM.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Yugo Nagata <nagata@sraoss.co.jp>
Discussion: https://postgr.es/m/ade0ab29-777f-47f6-9d0d-1af67728a86e@oss.nttdata.com