Description and goal

In all batching functions, we require a collection to collect into. This is unnecessary because diesel supports row streaming. We can only generate the streaming model functions and implement all others by default.

=> In all -Unchecked model batch traits, add a -_stream function that returns a TryStream, as provided by diesel's .load_stream. Then only generate this function in derive(Model). All others can be implemented by default using that.

Do not change the signatures of the current functions to avoid a massive refactoring (it'll come at some point since streams are superior, but one thing at a time).

The List trait can also benefit from a stream function.

Example for retrieve:

    fn retrieve_stream(
        conn: DbConnection,
        ids: impl IntoIterator<Item = K> + Send,
    ) -> impl futures::TryStream<Ok = Self, Error = Self::Error>;

This work should reduce the amount of generated code and reduce unnecessary allocations eventually.

Acceptance criteria

yes