refactor: redid the bindshell example

Made it use a single UDP client as well as proper randomized ports to go
through network firewalls, requiring stdin, status, stderr, and stdout
all go over a single UDP socket

Updated the client to have a prompt

examples/bind-shell/key-generator/src/lib.rs

@@ -14,4 +14,4 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 pub const PUBKEY: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/pubkey"));
-pub const PRIVKEY: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/pubkey"));
+pub const PRIVKEY: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/privkey"));