[SQL] Temporal filters are inhibited if `NOW()` is called by user-defined functions

The code generated for the following is substantially less efficient than the code that just inlines `CRT_DATE`.

```sql
CREATE FUNCTION CRT_DATE(T TIMESTAMP) RETURNS DATE AS CAST(T AS DATE);
CREATE TABLE T(D DATE, X INT);
CREATE VIEW V AS SELECT * FROM T WHERE T.D < CRT_DATE(NOW())
```