Support SSH onnections into a-shell (`sshd`)

I think it would be really useful to be able to ssh into a-shell from a computer for setup and experimentation (it's also useful for shortcuts although a-shell already supports them natively).
I read some of the `ios_system` code but I'm unfamiliar with iOS development and couldn't figure not exactly how it works, but it looks `sshd` is [already built](https://github.com/holzschu/ios_system/blob/master/ssh-agent/sshd.c) as part of `ssh-agent`..? If I understand correctly it needs to be a `ios_system` bulitin rather than a normal binary in order to properly handle establishing ssh connections?