Enable placement on more `scalar_fn`s to allow lowering and pushdown to `TableScan`s

We should use the new placement API for more scalar fns. This allows better query plans for example in vortex we get a large speed up for clickbench query q29 (below) when pushing down `OCTET_LENGTH("URL")` since we never need load the URL str bytes

```sql
SELECT "CounterID", AVG(OCTET_LENGTH("URL")) AS l, COUNT(*) AS c FROM hits WHERE "URL" <> '' GROUP BY "CounterID" HAVING COUNT(*) > 100000 ORDER BY l DESC LIMIT 25; -- ClickHouse's length counts bytes, not code points as standard SQL.
```

Scalar fn:

- [ ] bit/octet/''-length
- [ ] todo

Please add any more and we can update the list

Start with the placement API and trace the OCTET_LENGTH example through lowering to TableScan, using ClickBench query q29 as the concrete case. Identify additional scalar functions beyond the listed bit/octet/''-length items, add placement support for the selected functions, and confirm that eligible expressions can be pushed into the resulting plan.

Written by the indexing model from the issue text.