OS Support: Support MacOS in CI

[chorman0773]

macOS is a Posix Compliant operating system, and lc-coreutils should ideally build on macOS.
Presently, the use of the mknodat syscall has caused CI failures. This should be looked into (Note: do not replace *at syscalls in lc-coreutils).

• Assess Version of Posix Compliance presented by macOS
• Assess alternatives for missing 2008 functions, particularily the *at syscalls
• Determine if macOS Support is viable
• Reenable if possible, otherwise remove macos CI workflows