tests: unit: util: Add test for nested FOR_EACH call
tests: unit: util: Add test for nested FOR_EACH call

Added test for case were FOR_EACH call is nested.

Signed-off-by: Krzysztof Chruscinski <9b6dc988558c51b0405b49b55c8e66862969844b@nordicsemi.no>

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