Asyncify all the things

[fordN]

The streaming support that is in flight has highlighted the potential benefits of converting to using Asyncio and a compatible http async client to better handle long running background tasks. I don't think this is a vital feature; indeed, it may even make the application heavier and thus a bit slower; but it could have many benefits as the tasks being managed get more complex.

[abarmat]

I find it useful when building stuff over this library. I'm playing with a TUI to display the dataset and versions, and had to use asyncio.to_thread() to avoid locking the render loop when doing network. I think it'd look cleaner if the base lib was async.