invoicesrpc: create sub server

Sub server implementation is still empty. This is a preparatory
step for adding invoice functionality.

rpcserver.go

@@ -397,6 +397,7 @@ var _ lnrpc.LightningServer = (*rpcServer)(nil)
 func newRPCServer(s *server, macService *macaroons.Service,
 	subServerCgs *subRPCServerConfigs, serverOpts []grpc.ServerOption,
 	restServerOpts []grpc.DialOption, atpl *autopilot.Manager,
+	invoiceRegistry *invoices.InvoiceRegistry,
 	tlsCfg *tls.Config) (*rpcServer, error) {
 
 	var (
@@ -408,7 +409,7 @@ func newRPCServer(s *server, macService *macaroons.Service,
 	// the dependencies they need are properly populated within each sub
 	// server configuration struct.
 	err := subServerCgs.PopulateDependencies(
-		s.cc, networkDir, macService, atpl,
+		s.cc, networkDir, macService, atpl, invoiceRegistry,
 	)
 	if err != nil {
 		return nil, err