- use gossip_queries_req instead of initial_routing_sync
- add connected nodes to recent peers only after successful init
- derive timestamp used with gossip_timestamp_filter from channel_db
- fix query_short_channel_ids:
1. channel IDs must be sorted with zlib
2. limit request to 100
3. do not abuse this to request node_announcements; it is fine not to have all nodes.
- fix get_recent_peers:
1. do not set last_connected_date to 'now' if we never connected a node
2. sql query was misconstructed and was returning only one peer
- populate FALLBACK_NODE_LIST_MAINNET with nodes that have the requested flags
