added aarch64-linux-gnu and mac-M1 implementation for context switch

Tested and built in arm64v8/ubuntu:20.04 container using docker+qemu integration

root@9cd427ad38ff:/workspace/cmake-aarch64-container/tests/bin# uname -a
Linux 9cd427ad38ff 5.11.0-41-generic #45~20.04.1-Ubuntu SMP Wed Nov 10 10:20:10 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux

root@9cd427ad38ff:/workspace/cmake-aarch64-container/tests/bin# ./context_tests 
Compiler: Clang 10.0.0 
Run tests in subprocesses (set --disable-forks flag to disable forks)
--------------------------------------------------------------------------------
Test 'SwitchContext' from suite 'ExecutionContext1' is running...
Executed in subprocess with pid = 13339
Parent
Parent
Parent

PASSED (0.15 seconds)
--------------------------------------------------------------------------------
Test 'MainThread' from suite 'ThreadStack' is running...
Executed in subprocess with pid = 13346
This thread stack: {0x5500001000, 8388608}

PASSED (0.10 seconds)
--------------------------------------------------------------------------------
ALL 2 TESTS PASSED! (Total time: 0.28 seconds)
~(˘▾˘~)