component: accept TURN in nice_component_verify_remote_candidate()

When TURN is in operation, agent_recv_message_unlocked() may receive from
NiceSocket with type = NICE_SOCKET_TYPE_UDP_TURN. Such messages were always
dropped due to failed nice_component_verify_remote_candidate().
Differential Revision: https://phabricator.freedesktop.org/D1727
Status Job ID Name Coverage
  Build
passed #4930
build-and-test

00:01:00