Add regression tests for missing json functions and operators

Author: Nikita Glukhov

src/test/regress/expected/create_table.out

@@ -196,6 +196,9 @@ CREATE TABLE array_index_op_test (
 	i			int4[],
 	t			text[]
 );
+CREATE TABLE testjson (
+       j json
+);
 CREATE TABLE testjsonb (
        j jsonb
 );