dependency on a platform independent serial port library so that vfloppy can build for linux, mac, and windows

[mk2s]

I would like to propose introducing a dependency on a serial port library so that we can build for linux, mac, and windows.

Currently the code depends on termios.h which is very unix specific. I've seen alternatives such as:

1. libserialport
2. Qt which includes serial port
3. https://github.com/wjwwood/serial
4. https://github.com/Marzac/rs232/tree/master

I have a PoC that compiles and runs on windows here The PoC was to see how hard it would be, and it seems reasonable. I have chosen libserialport arbitrarily for my PoC and have not looked much at other alternatives. If we proceed I would change to use the library in all cases instead of #ifdef WIN32 and remove #include <termios.h>.

This issue is mostly to start a conversation and to see if there were other requirements the Author/Maintainers have.

Also I would like to propose switching the build system from make to zig and the tool chain from whatever it currently is to zig. Zig can build for all linux from one job and probably can build for macos from the same job. If the job is run on windows I think it might be able to build for all linux, macos, and windows.(I have not tried this, but I have tried build with zig and it does work for linux and windows) Zig also handles the dependency such that as part of building vfloppy it will download and build libserialport as well.

Thank you for all your work for the px-8/hc-80 community.