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: https://postgr.es/m/
20200728170408.GI20393@telsasoft.com