tests: posix: headers: net: Add various IPv6 address check macros

Add these Posix specified IPv6 address checking macros

IN6_IS_ADDR_UNSPECIFIED
IN6_IS_ADDR_LOOPBACK
IN6_IS_ADDR_MULTICAST
IN6_IS_ADDR_LINKLOCAL
IN6_IS_ADDR_SITELOCAL
IN6_IS_ADDR_V4MAPPED
IN6_IS_ADDR_MC_NODELOCAL
IN6_IS_ADDR_MC_LINKLOCAL
IN6_IS_ADDR_MC_SITELOCAL
IN6_IS_ADDR_MC_ORGLOCAL
IN6_IS_ADDR_MC_GLOBAL

and tests for them.

Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>