refactor+multi: use *lnwire.FeatureVector for ChannelEdgeInfo features

In this commit, we move the serialisation details of a channel's
features to the DB layer and change the `models` field to instead use a
more useful `*lnwire.FeatureVector` type.

This makes the features easier to work with and moves the serialisation
to where it is actually used.

routing/localchans/manager.go

@@ -305,13 +305,6 @@ func (r *Manager) createEdge(channel *channeldb.OpenChannel,
 		channelFlags = 1
 	}
 
-	var featureBuf bytes.Buffer
-	err := lnwire.NewRawFeatureVector().Encode(&featureBuf)
-	if err != nil {
-		return nil, nil, fmt.Errorf("unable to encode features: %w",
-			err)
-	}
-
 	// We need to make sure we use the real scid for public confirmed
 	// zero-conf channels.
 	shortChanID := channel.ShortChanID()
@@ -323,7 +316,7 @@ func (r *Manager) createEdge(channel *channeldb.OpenChannel,
 	info := &models.ChannelEdgeInfo{
 		ChannelID:    shortChanID.ToUint64(),
 		ChainHash:    channel.ChainHash,
-		Features:     featureBuf.Bytes(),
+		Features:     lnwire.EmptyFeatureVector(),
 		Capacity:     channel.Capacity,
 		ChannelPoint: channel.FundingOutpoint,
 	}

routing/localchans/manager_test.go

@@ -387,7 +387,7 @@ func TestCreateEdgeLower(t *testing.T) {
 	expectedInfo := &models.ChannelEdgeInfo{
 		ChannelID:     8,
 		ChainHash:     channel.ChainHash,
-		Features:      []byte{0, 0},
+		Features:      lnwire.EmptyFeatureVector(),
 		Capacity:      9,
 		ChannelPoint:  channel.FundingOutpoint,
 		NodeKey1Bytes: sp,
@@ -475,7 +475,7 @@ func TestCreateEdgeHigher(t *testing.T) {
 	expectedInfo := &models.ChannelEdgeInfo{
 		ChannelID:     8,
 		ChainHash:     channel.ChainHash,
-		Features:      []byte{0, 0},
+		Features:      lnwire.EmptyFeatureVector(),
 		Capacity:      9,
 		ChannelPoint:  channel.FundingOutpoint,
 		NodeKey1Bytes: rp,

routing/pathfind_test.go

@@ -348,6 +348,7 @@ func parseTestGraph(t *testing.T, useCache bool, path string) (
 			ChannelID:    edge.ChannelID,
 			AuthProof:    &testAuthProof,
 			ChannelPoint: fundingPoint,
+			Features:     lnwire.EmptyFeatureVector(),
 			Capacity:     btcutil.Amount(edge.Capacity),
 		}
 
@@ -677,6 +678,7 @@ func createTestGraphFromChannels(t *testing.T, useCache bool,
 			AuthProof:    &testAuthProof,
 			ChannelPoint: *fundingPoint,
 			Capacity:     testChannel.Capacity,
+			Features:     lnwire.EmptyFeatureVector(),
 
 			NodeKey1Bytes:    node1Vertex,
 			BitcoinKey1Bytes: node1Vertex,

routing/router_test.go

@@ -2741,6 +2741,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 		NodeKey2Bytes:    pub2,
 		BitcoinKey1Bytes: pub1,
 		BitcoinKey2Bytes: pub2,
+		Features:         lnwire.EmptyFeatureVector(),
 		AuthProof:        nil,
 	}
 	require.NoError(t, ctx.graph.AddChannelEdge(ctxb, edge))
@@ -2816,6 +2817,7 @@ func TestAddEdgeUnknownVertexes(t *testing.T) {
 
 	edge = &models.ChannelEdgeInfo{
 		ChannelID: chanID.ToUint64(),
+		Features:  lnwire.EmptyFeatureVector(),
 		AuthProof: nil,
 	}
 	copy(edge.NodeKey1Bytes[:], node1Bytes)