Each waypipe server instance now can optionally open a "control pipe"
in the file system; when a socket path is written to the pipe, the
root waypipe server instance will try to establish new connections with
the waypipe client for each connected Wayland client, and if successful,
send each subprocess handler its new connection fd. To ensure that the
waypipe client also can updated its subprocess handlers with the
new connections, each Wayland client is assigned a random identifying
token.