End to end testing for SOCKS5

[rlahfa-dinum]

This provides basic end-to-end testing for SOCKS5:

• Direct CONNECT scenario (autonomous operations)
• Chained CONNECT scenario to another third party SOCKS5 server (microsocks here)

As we grow our functionalities, we should add more testing:

• rejection testing once ACL is here
• redirection testing once ACL is here
• metadata testing once trust inference is here
• tinyproxy upstream testing once feat: add http connect #30 is merged
• mTLS client testing once proxy: enable (m)TLS on the server side #27 is merged via stunnel probably
• mTLS server testing once state: enable mTLS on the client side #28 is merged via NGINX client certs
• testing to pass large frames larger than MTU (fragmentation testing)
• testing upstream rejections propagation

Some special scenarios as well:

• IMAP/SMTP testing
• UDP testing, e.g. by deploying Visio (perhaps with multiple firewall topologies)

But for now, this is a good start.