PostgreSQL compatibility: negative array subscripts should not index from the end

Split out from #22247.

### Mismatch

Negative array subscripts should not index from the end.

```sql
SELECT (array[10,20,30])[-1];
```

PostgreSQL:

```text
NULL
```

DataFusion:

```text
30
```

### Expected behavior

For PostgreSQL-compatible SQL semantics, DataFusion should either match PostgreSQL's result or raise the same class of domain/semantic error.