Cover the new fd-direct connect path: stream connect and data passing,
the peer address reported by getpeername(2), datagram to an unbound
peer, the EINVAL/ENOTSOCK/EPROTOTYPE/ECONNREFUSED error matrix,
and the Capsicum token semantics — a descriptor limited to
CAP_CONNECTAT can be connected to but not listened on, accepted from,
or read, and one lacking CAP_CONNECTAT cannot be a connect target.
Stream listeners are always bound: uipc_listen() refuses unbound
sockets with EDESTADDRREQ, so an unbound fd-direct listener is not
reachable even with this feature.
Signed-off-by: John Ericson <John.Ericson@Obsidian.Systems>