Fix building for Zephyr V3.6, QNX and other platforms that don't supp…

[PatrickM-ZS]

This PR targets embedded builds (Zephyr, QNX) with the following changes:

• Fix some minor issues introduced recently that caused builds without single-source multicast and dynamic library loading support to fail
• Update Zephyr port to support latest version V3.6.0[https://docs.zephyrproject.org/latest/releases/release-notes-3.6.html]
• Support building unit-tests for QNX. Note to run tests you'll need to set the CMAKE_CROSSCOMPILING_EMULATOR variable to a script that executes the binary on eg. qemu or uses tools like ftp, ssh or telnet to upload and execute it on a remote target.