Debloat your async Rust

This is something I'm currently dealing with at work because we decided fairly early on to use async streams.

Overall, I have to say it is a pleasant enough interface to use, but the bloat is real, opening tokio-console shows a dozen futures with sizes well in the 5000 bytes, and not using/not understanding how pin-project works early-on lead to a whole lot of extra Pin<Box<_>> in structs, absolutely trashing the heap with small allocations.

Async Rust, as it is right now, makes it really easy to shoot yourself in the foot. I highly recommend turning on clippy large-futures when starting a new async Rust project.