Avoid re-evaluating expressions in filters and projections

This patterns shows up pretty often:

```sql
select expensive(col)
from t
where expensive(col)
```

A pathological case is variant / json:

```sql
select variant_get(col, 'key')
from t
from variant_get(col, 'key')
```

There's two issues here:
1. Until we solve projection pushdown (https://github.com/apache/datafusion/issues/14993) if `key` is not shredded we materialize the entire `col` and then extract `key` in a `ProjectionExec`.
2. Even once that is resolved, or in the case that `key` is not shredded evaluating `variant_get(col, 'key')` itself is expensive we still re-compute `variant_get(col, 'key')` twice: once for the filter and once for the projection.

まず、SQL の例で説明されているフィルターとプロジェクションの動作を読み、ProjectionExec と projection-pushdown の issue #14993 も確認します。variant_get(col, 'key') のような繰り返し式がどのように表現され、評価されるかを判断し、そのうえで、クエリ結果を維持しながら重複した評価を避けることを完了条件として定義します。

索引モデルが issue の本文から書いたものです。