config: rename Vochain.OffChainDataDownloader

cmd/node calls the flag vochainOffChainDataDownload,
and viper unmarshals that to our config struct,
meaning that after our recent viper cleanup the field was now dangling.

Rather than adding another special case or renaming the flag,
since the only user of the config field is cmd/node itself,
rename the field to be consistent with the flag and YAML.

cmd/node/main.go

@@ -465,16 +465,16 @@ func main() {
 		conf.Vochain.IsSeedNode = types.ModeSeed == conf.Mode
 		// do we need indexer?
 		conf.Vochain.Indexer.Enabled = conf.Mode == types.ModeGateway
-		// offchainDataDownloader is only needed for gateways
-		conf.Vochain.OffChainDataDownloader = conf.Vochain.OffChainDataDownloader &&
+		// offchainDataDownload is only needed for gateways
+		conf.Vochain.OffChainDataDownload = conf.Vochain.OffChainDataDownload &&
 			conf.Mode == types.ModeGateway
 
 			// create the vochain service
 		if err = srv.Vochain(); err != nil {
 			log.Fatal(err)
 		}
 		// create the offchain data downloader service
-		if conf.Vochain.OffChainDataDownloader {
+		if conf.Vochain.OffChainDataDownload {
 			if err := srv.OffChainDataHandler(); err != nil {
 				log.Fatal(err)
 			}

config/config.go

@@ -126,7 +126,7 @@ type VochainCfg struct {
 	// IsSeedNode specifies if the node is configured to act as a seed node
 	IsSeedNode bool
 	// OffChainDataDownload specifies if the node is configured to download off-chain data
-	OffChainDataDownloader bool
+	OffChainDataDownload bool
 }
 
 // IndexerCfg handles the configuration options of the indexer