Instead of using net_context API directly, the DNS resolver is changed to use the socket service API. This allows DNS access for offloaded sockets and can lower overall memory consumption. Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>
Added tests in order to verify the functionality of the newly added DNS cache. Signed-off-by: Carlo Kirchmeier <carlo.kirchmeier@zuehlke.com>