tests: net: iface: Add test for net_if_ipv6_select_src_iface()
tests: net: iface: Add test for net_if_ipv6_select_src_iface()

Make sure that net_if_ipv6_select_src_iface() returns correct network
interface for a given destination address.

Signed-off-by: Jukka Rissanen <f9f077d1da4c7aa947f9864fa5a28c3588f6a45d@linux.intel.com>

finikorg/zephyr,kraj/zephyr,ldts/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,ldts/zephyr,explora26/zephyr,punitvara/zephyr,nashif/zephyr,explora26/zephyr,explora26/zephyr,ldts/zephyr,nashif/zephyr,punitvara/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,kraj/zephyr,finikorg/zephyr,Vudentz/zephyr,finikorg/zephyr,kraj/zephyr,finikorg/zephyr,ldts/zephyr,punitvara/zephyr,kraj/zephyr,ldts/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,nashif/zephyr,punitvara/zephyr,kraj/zephyr,galak/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,explora26/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr