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

.devcontainer/Dockerfile.buster

@@ -25,7 +25,7 @@ ENV DEBIAN_FRONTEND=noninteractive \
     VISUAL='code -w'
 
 RUN apt-get update && \
-    apt install -y cmake git libtool valgrind docker-compose lldb sudo zsh wget && \
+    apt install -y cmake git libtool valgrind docker-compose lldb sudo zsh wget tmux && \
     apt-get autoremove -y && apt-get clean -y && rm -rf /var/lib/apt/lists/* && \
     adduser ${USERNAME} && \
     echo "$USERNAME ALL=(ALL:ALL) NOPASSWD: ALL" >> /etc/sudoers && \