s3:smbd multichannel: always refresh the network information

s3:smbd multichannel: always refresh the network information

To maintain SMB Multichannel, windows client might periodically query with
FSCTL_QUERY_NETWORK_INTERFACE_INFO to get SMB server's network information,
in my case windows server 2022 would do this every 10 minutes (600 seconds).

Consider a scenario: the network information might have changed between
these queries, some become link down, new interface is link up, network
speed is changed, and etc. So far smbd might not aware of these changes and
still report out-of-date network information to windows client, until we
manually send a SIGHUP to smbd in order to trigger load_interfaces():
smbd_sig_hup_handler() > reload_services () > load_interfaces()
This might be a bit inconvenient because it is hard to decide when should
we manually send a SIGHUP to smbd for refreshing network information.

This patch adds load_interfaces() at fsctl_network_iface_info(), while smbd
received FSCTL_QUERY_NETWORK_INTERFACE_INFO would go through this and refresh
local_interfaces, then respond to client with up-to-date network information;
also refresh num_ifaces to make sure interfaces count is consistent.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15547

Signed-off-by: Jones Syue <jonessyue@qnap.com>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Björn Jacke <bjacke@samba.org>