feat: allow different send & receive ports

[umbertov]

Noticed that the --port CLI argument, and the GUI "Port" field, only indicate the port that the linux program will listen on, not the one where it will send the data, which was hardcoded to 8321. It is not possible to modify the listening port without rebuilding the executable.

This PR does the following:

• rename the variables like stream_port to listen_port,
• rename CLI argument --port to --listen-port
• rename GUI field from "Port" to "Listen Port"
• introduce CLI argument --connect-port which is used in setup_recv_socket
• introduce GUI field "Connect Port" which is the GUI counterpart to --connect-port

[ripxorip]

Hi @umbertov , thank you for your PRs, I would love to merge them. I have been working hard on a significant improvement in #4 , I will try to get this merged over the weekend then we can perhaps rebase the your PRs onto that? It adds support for a few of the features you have implemented, but most importantly for different audio backends such as ALSA directly.

[umbertov]

hey @ripxorip yea sure.

I could even change the base of the PR to #4's branch if that makes matters easier. Otherwise we can wait to merge #4 & then i'll rebase