pgsql: Include partitioned tables for tab completion of VACUUM in psql

Include partitioned tables for tab completion of VACUUM in psql

The relkinds that support indexing are the same as the ones supporting
VACUUM, so the code gets refactored a bit with the completion query used
for CLUSTER, but there is no change for CLUSTER in this commit.

Author: Justin Pryzby
Reviewed-by: Fujii Masao, Michael Paquier, Masahiko Sawada
Discussion: /messages/by-id/20200728170408.GI20393@telsasoft.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/f1af75c5f2516ec5b20cfe4b3a474071a318ae1e

Modified Files
--------------
src/bin/psql/tab-complete.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)