test(io): refactor SQL fixtures

- Move privileges and grants to privileges.sql
- Move schema, tables and functions to schema.sql
- Move global database settings to database.sql

Signed-off-by: Taimoor Zaeem <taimoorzaeem@gmail.com>

test/io/fixtures/database.sql

@@ -0,0 +1,2 @@
+SET check_function_bodies = false; -- to allow conditionals based on the pg version
+SET search_path = public;