The API is now synchronous and any quinn stuff has been moved to another
package. The quinn stuff will be slowly moved into moq-transport with
generic traits.
I miss quiche, but it was a pain to do anything asynchronous. MoQ is a
pub/sub protocol so it's very important to support subscribers
joining/leaving/stalling. The API is also just significantly better
since quinn doesn't restrict itself to C bindings, which I'm sure will
come back to haunt me when we want OBS support.