[Feature] Add `[must_use]` attribute and implement `IntoFuture` for `D1PreparedStatement`

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Description

`D1PreparedStatement` is just a statement, which has not been executed actually. However, user could make mistake by writing code like this:
```rust
query!(&self.db, "DELETE FROM users WHERE id = ?", id)?; // correct version: query!(&self.db, "DELETE FROM users WHERE id = ?", id)?.all().await?
```
This code does not work, `D1PreparedStatement` just like a `Future` in Rust. It wouldn't been executed automatically, it must been called explicitly .

I suggest that we could implement `IntoFuture` for `D1PreparedStatement`, so that we can execute a statement by `await` it directly. What's more, `D1PreparedStatement` need to been attributed as `#[must_use]`, to avoid misuse statically.