libnm/keyfile: ignore [wifi].seen-bssids for keyfile

"seen-bssids" primarily gets stored to "/var/lib/NetworkManager/seen-bssids",
it's not a regular property.

We want this property to be serialized/deserialized to/from GVariant,
because we expose these settings on the API like a property of the
profile. But it cannot be modified via nmcli, it cannot be stored
to ifcfg files, and it makes not sense to store it to keyfile either.

Stop doing that.

(cherry picked from commit d9ebcc8646)

src/libnm-core-impl/nm-keyfile.c

@@ -2781,6 +2781,9 @@ static const ParseInfoSetting *const parse_infos[_NM_META_SETTING_TYPE_NUM] = {
                                 .parser = mac_address_parser_ETHER_cloned, ),
             PARSE_INFO_PROPERTY(NM_SETTING_WIRELESS_MAC_ADDRESS,
                                 .parser = mac_address_parser_ETHER, ),
+            PARSE_INFO_PROPERTY(NM_SETTING_WIRELESS_SEEN_BSSIDS,
+                                .parser_skip = TRUE,
+                                .writer_skip = TRUE, ),
             PARSE_INFO_PROPERTY(NM_SETTING_WIRELESS_SSID,
                                 .parser = ssid_parser,
                                 .writer = ssid_writer, ), ), ),