tests: add new futex test
tests: add new futex test

Add new standalone futex test that verifies next requirements:
-Futex can be placed in user memory using ZTEST_BMEM
-User thread can write to futex value
-User threads can make wait/wake syscalls on it

Added detailed Doxygen tag with information about the test

Signed-off-by: Maksim Masalski <00762c94550ce68b2a0e3f1373f5a19cd4f4bbbb@intel.com>

Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr,galak/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,nashif/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,nashif/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,Vudentz/zephyr,nashif/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,Vudentz/zephyr,finikorg/zephyr