Allow specifying Network Proxy (HTTP/HTTPS/SOCKS)

[Azathothas]

rustup allows proxies if we set certain env vars: https://rust-lang.github.io/rustup/network-proxies.html
https_proxy
https_proxy

But we should have a dedicated --proxy option to allow users to specify any kind of proxy, similar to curl..
The major use case here will be for users behind firewalls that can't access Github (Our primary repos are on ghcr), or just want to use another connection for soar
This option should also be included in SOAR_CONFIG file