Convert indexed ARRAY_AGG to NTH_VALUE

### Is your feature request related to a problem or challenge?

Query below
```sql
SELECT a, ARRAY_AGG(c ORDER BY c)[1] as result
FROM multiple_ordered_table
GROUP BY a;
```
and
```sql
SELECT a, NTH_VALUE(c, 1 ORDER BY c) as result
FROM multiple_ordered_table
GROUP BY a;
```
produces same results. However, first query generates following plan
```
"ProjectionExec: expr=[a@0 as a, (ARRAY_AGG(multiple_ordered_table.c) ORDER BY [multiple_ordered_table.c ASC NULLS LAST]@1).[1] as result]",
" AggregateExec: mode=Single, gby=[a@0 as a], aggr=[ARRAY_AGG(multiple_ordered_table.c)], ordering_mode=Sorted",
" CsvExec: file_groups={1 group: [[CSV_PATH]]}, projection=[a, c], output_orderings=[[a@0 ASC NULLS LAST], [c@1 ASC NULLS LAST]], has_header=true",
```
whereas second query generates following plan
```
"ProjectionExec: expr=[a@0 as a, NTH_VALUE(multiple_ordered_table.c,Int64(1)) ORDER BY [multiple_ordered_table.c ASC NULLS LAST]@1 as result]",
" AggregateExec: mode=Single, gby=[a@0 as a], aggr=[NTH_VALUE(multiple_ordered_table.c,Int64(1))], ordering_mode=Sorted",
" CsvExec: file_groups={1 group: [[CSV_PATH]]}, projection=[a, c], output_orderings=[[a@0 ASC NULLS LAST], [c@1 ASC NULLS LAST]], has_header=true",
```

### Describe the solution you'd like

we can rewrite first query as second one, which executes faster with less memory. Because it no longer needs to keep all results in the array_agg.

### Describe alternatives you've considered

_No response_

### Additional context

_No response_

Start with the two SQL examples and compare their displayed execution plans, focusing on the indexed ARRAY_AGG expression and the NTH_VALUE equivalent. Verify that the proposed rewrite preserves results while avoiding retention of the full array and reducing memory use.

Written by the indexing model from the issue text.