MINOR: receiver: move the FOREIGN and V6ONLY options from listener to settings

MINOR: receiver: move the FOREIGN and V6ONLY options from listener to settings

The new RX_O_FOREIGN, RX_O_V6ONLY and RX_O_V4V6 options are now set into
the rx_settings part during the parsing, so that we don't need to adjust
them in each and every listener anymore. We have to keep both v4v6 and
v6only due to the precedence from v6only over v4v6.