Add `get_term_size` to other platforms

[RaphGL]

Terminal size outside of windows and linux is retrieved by moving the cursor to a ridiculously high coordinate and then asking the terminal to tell us where the cursor ended up. This works as a fallback but ideally we should get this information from the OS.

Missing OS implementations:

• MacOS
• FreeBSD
• NetBSD
• OpenBSD

This is an non comprehensive list and probably should be an ongoing effort. Personally I don't have any of these operating systems installed so any help would be appreciated!