Add support for -D (SOCKS5 dynamic proxy) as well as -L and -R?

[srk]

Add support for -D (SOCKS5 dynamic proxy) as well as -L and -R?

[rustonbsd]

Hi @srk, -L and -R are already supported with standard addressess like localhost or IPs but not EndpointId's yet.

For a VNC example using the -N flag with iroh-ssh see the following video I made: https://www.youtube.com/watch?v=gfwBilBQzzM

-D is a good idea, I will add it in with the iroh relay and dns PR #22

Thank you for the suggestion!