Placeholder types not inferred for `date_bin` (and possibly other functions depending on the signature)

```sql
explain select date_bin($resolution::interval, now());
```

Fails with:

```
Error during planning: Failed to coerce arguments to satisfy a call to 'date_bin' function: coercion from Null, Timestamp(ns) to the signature ...
```

I'm not sure if something could be done here, but I wanted to note it.

cc @phillipleblanc 