graph/db: let ForEachNode take a context

autopilot/graph.go

@@ -123,7 +123,7 @@ func (d *dbNode) ForEachChannel(ctx context.Context,
 func (d *databaseChannelGraph) ForEachNode(ctx context.Context,
 	cb func(context.Context, Node) error) error {
 
-	return d.db.ForEachNode(func(nodeTx graphdb.NodeRTx) error {
+	return d.db.ForEachNode(ctx, func(nodeTx graphdb.NodeRTx) error {
 		// We'll skip over any node that doesn't have any advertised
 		// addresses. As we won't be able to reach them to actually
 		// open any channels.

autopilot/interface.go

@@ -228,7 +228,7 @@ type GraphSource interface {
 	// the callback returns an error, then the transaction is aborted and
 	// the iteration stops early. Any operations performed on the NodeTx
 	// passed to the call-back are executed under the same read transaction.
-	ForEachNode(func(graphdb.NodeRTx) error) error
+	ForEachNode(context.Context, func(graphdb.NodeRTx) error) error
 
 	// ForEachNodeCached is similar to ForEachNode, but it utilizes the
 	// channel graph cache if one is available. It is less consistent than