🗑 async-dropper-derive

async-dropper is probably the least-worst ad-hoc AsyncDrop implementation you've seen, and it works in two ways:

• async_dropper::simple is stolen nearly verbatim from this StackOverflow answer (thanks to paholg!)
• async_dropper::derive provides a trait called AsyncDrop and corresponding [derive macro][rust-derive-macro], which try to use Default and PartialEq to determine when to async drop.

The code in this crate powers async_dropper::derive. See the async_dropper crate for more details.