Add Cursor API?

I've been writing a [collection API](https://github.com/DropDemBits/rust-ndis-examples/blob/c09e42f87c749be338305223f7ebf832a3e4d57b/driver/wdf-kmdf/src/collection.rs) on top of this crate, but I've realized that I can't use `retain` without either leaking memory or invoking undefined behaviour. Is there an interest in supporting a Cursor API on top of the original list structs?