Each known network (previously connected) will have a set
of known frequencies associated with it, e.g. a set of
frequencies from all BSSs observed. The list of known
frequencies is sorted with the most recently observed
frequency in the head.
Until now network.c managed the list of network_info structs including
for known networks and networks that are seen in at least one device's
scan results, with the is_known flag to distinguish known networks.
Each time the list was processed though the code was either interested
in one subset of networks or the other. Split the list into a Known
Networks list and the list of other networks seen in scans. Move all
code related to Known Networks to knownnetworks.c, this simplifies
network.h. It also gets rid of network_info_get_known which actually
returned the list of all network_infos (not just for known networks),
which logically should have been private to network.c. Update device.c
and scan.c to use functions specific to Known Networks instead of
filtering the lists by the is_known flag.
This will also allow knownnetworks.c to export DBus objects and/or
properties for the Known Networks information because it now knows when
Known Networks are added, removed or modified by IWD.
knownnetworks.c/.h implements the KnownNetworks interface and loads the
known networks from storage on startup. The list of all the networks
including information on whether a network is known is managed in
network.c to avoid having two separate lists of network_info structures
and keeping them in sync. That turns out to be difficult because the
network.c list is sorted by connected_time and connected_time changes
can be triggered in both network.c or knownnetworks.c. Both can also
trigger a network_info to be removed completely.
