pgsql: amcheck: Add a test with GIN index on JSONB data

amcheck: Add a test with GIN index on JSONB data

Extend the existing test of GIN checks to also include an index on JSONB
data, using the jsonb_path_ops opclass. This is a common enough usage of
GIN that it makes sense to have better test coverage for it.

Author: Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com>
Reviewed-By: Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>
Reviewed-By: Kirill Reshke <reshkekirill(at)gmail(dot)com>
Discussion: https://postgr.es/m/BC221A56-977C-418E-A1B8-9EFC881D80C5%40enterprisedb.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/ca738bdc4c9d32c05a6abd125ce495dfb82be492

Modified Files
--------------
contrib/amcheck/expected/check_gin.out | 14 ++++++++++++++
contrib/amcheck/sql/check_gin.sql | 12 ++++++++++++
2 files changed, 26 insertions(+)