NAN USD: Add publishChannelList option for Subscriber

NAN USD: Add publishChannelList option for Subscriber

Add frequency list to active NAN USD Subscriber to search for a
Publisher on multiple channels. This is the publish channel list used by
the Subscriber to periodically search for a service on these channels.
publishChannelList was already supported in the Publisher and this
commit extends that to the Subscriber.

This is needed for a P2P2 seeker that is an active subscriber looking
for an advertiser on a list of publish channels.

Signed-off-by: Shivani Baranwal <quic_shivbara@quicinc.com>