ORDER BY alias does not work with RETURN AS alias

**Describe the bug**
ORDER BY alias does not work with RETURN AS alias

**How are you accessing AGE (Command line, driver, etc.)?**
- Command Line

**What data setup do we need to do?**
```pgsql
SELECT * FROM cypher('graph', $$
CREATE (:opt_match_v {name: 'someone'})-[:opt_match_e]->(:opt_match_v {name: 'somebody'}),
(:opt_match_v {name: 'anybody'})-[:opt_match_e]->(:opt_match_v {name: 'nobody'})
$$) AS (u agtype);
```

**What is the command that caused the error?**
```pgsql
SELECT * FROM cypher('graph', $$
MATCH p=(n)-[]->(m)
RETURN n.name as u
ORDER BY u
$$) AS (u agtype);
```
```
ERROR: could not find rte for u
LINE 2: MATCH p=(n)-[]->(m) RETURN n.name as u ORDER BY u
^
```

**Expected behavior**
Expected order by to work

**Environment (please complete the following information):**
- latest