async_refactor branch checklist

[osa1]

Stuff to be done before release:

• Finish logging
• Address name resolving step should be interruptible -- currently I can't do e.g. /connect if the task is blocked on getsockaddr(). Similarly I can't quit.
• SASL authentication
• Implement sending pings on timeout.
• Reconnecting after a disconnect does not work.
• C-c does not really quit -- it closes the connections (I think, at least it sends QUIT messages) but the TUI hangs.
• Port 1d2a690
• Find a way to disable stderr logging in release build Use env_logger for debug logs

[osa1]

Almost done!

[osa1]

There are still a few awaits in the client main loop that blocks the client; those should be refactored:

• The addr_iter await call
• The delay when address name resolve fails
• The delay when connection fails (after address name resolving)

Also, it seems like we currently try to reconnect immediately when connection fails after it's established. This is different than the previous behavior where we waited for 30 seconds or so.

[osa1]

We have PR now and we'll track progress there.