Fix inconsistencies with pg_restore --statistics[-only]

Fix inconsistencies with pg_restore --statistics[-only]

Attempting to restore a schema, a table or an index with
--only-statistics skipped all the statistics of the objects wanted.
Like for pg_dump, statistics should be included, so this created an
assymetry between dump and restore.

A second set of problems existed for --table and --index, where the
presence of --statistics skipped the restore of the stats of the
object(s) targetted.

This issue has been reported originally as related to an inconsistency
with the way extended stats restore is handled in Postgres v19, but the
issue is related to the restore of relation and attribute statistics in
v18.  Some TAP tests are added to cover all these cases.

Reported-by: Chao Li <li.evan.chao@gmail.com>
Author: Chao Li <li.evan.chao@gmail.com>
Author: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Discussion: https://postgr.es/m/66E80CAB-527C-42B1-BB65-3F82CF4AD998@gmail.com
Backpatch-through: 18