multi: move block epochs dependency from links to switch

In this commit, we move the block height dependency from the links in
the switch to the switch itself. This is possible due to a recent change
on the links no longer depending on the block height to update their
commitment fees.

We'll now only have the switch be alerted of new blocks coming in and
links will retrieve the height from it atomically.

server.go

@@ -284,6 +284,11 @@ func newServer(listenAddrs []string, chanDB *channeldb.DB, cc *chainControl,
 			debugPre[:], debugHash[:])
 	}
 
+	_, currentHeight, err := s.cc.chainIO.GetBestBlock()
+	if err != nil {
+		return nil, err
+	}
+
 	s.htlcSwitch, err = htlcswitch.New(htlcswitch.Config{
 		DB:      chanDB,
 		SelfKey: s.identityPriv.PubKey(),
@@ -313,7 +318,8 @@ func newServer(listenAddrs []string, chanDB *channeldb.DB, cc *chainControl,
 		SwitchPackager:         channeldb.NewSwitchPackager(),
 		ExtractErrorEncrypter:  s.sphinx.ExtractErrorEncrypter,
 		FetchLastChannelUpdate: fetchLastChanUpdate(s, serializedPubKey),
-	})
+		Notifier:               s.cc.chainNotifier,
+	}, uint32(currentHeight))
 	if err != nil {
 		return nil, err
 	}