Allow PATCH/DELETE w/o Prefer when no SELECT privs

PATCH/DELETE can now be done without adding Prefer return=minimal when
the user doesn't have SELECT privileges.

* Also fix PATCH wrong HTTP status code

test/fixtures/privileges.sql

@@ -123,6 +123,10 @@ GRANT SELECT (article_id, user_id) ON TABLE limited_article_stars TO postgrest_t
 GRANT INSERT (article_id, user_id) ON TABLE limited_article_stars TO postgrest_test_anonymous;
 GRANT UPDATE (article_id, user_id) ON TABLE limited_article_stars TO postgrest_test_anonymous;
 
+GRANT SELECT(id, email) ON TABLE app_users TO postgrest_test_anonymous;
+GRANT INSERT, UPDATE    ON TABLE app_users TO postgrest_test_anonymous;
+GRANT DELETE            ON TABLE app_users TO postgrest_test_anonymous;
+
 REVOKE EXECUTE ON FUNCTION privileged_hello(text) FROM PUBLIC; -- All functions are available to every role(PUBLIC) by default
 GRANT EXECUTE ON FUNCTION privileged_hello(text) TO postgrest_test_author;