Support Postgres' JSON_OBJECT function RETURNING clause #2000
Description
json_object() supports quite broad syntax:
json_object ( [ { key_expression { VALUE | ':' } value_expression
[ FORMAT JSON [ ENCODING UTF8 ] ] }[, ...] ] [ { NULL | ABSENT } ON NULL ]
[ { WITH | WITHOUT } UNIQUE [ KEYS ] ]
[ RETURNING data_type [ FORMAT JSON [ ENCODING UTF8 ] ] ])
#1545 added support for the VALUE keyword between values. I now need support for RETURNING JSONB, as used by Django on Postgres 16+.