Hey all, I need some opinions. I want to make `sequential-storage` support async.
The idea is to move everything to be async and make the blocking API use that with a simple block_on executor and a compatibility layer for the `embedded-storage` traits.

There's a problem though. I don't think I can support cancellation. To make the flash state not be corrupt, sometimes two separate writes (or an erase) have to happen.

So how to deal with this? What do y'all like best?
- Don't deal with it and document it.
- Implement drop for all futures that on drop falls back to doing it blockingly.
- Don't do async if it cannot be properly supported.
- Something else?