fix: check for wallet tx batching support

lib/plugins/wallet/bitgo/bitgo.js

@@ -157,6 +157,11 @@ function cryptoNetwork (account, cryptoCode, settings, operatorId) {
     .then(() => account.environment === 'test' ? 'test' : 'main')
 }
 
+function supportsBatching (account, cryptoCode) {
+  return checkCryptoCode(cryptoCode)
+    .then(() => _.isFunction(sendCoinsBatch))
+}
+
 module.exports = {
   NAME,
   balance,
@@ -164,5 +169,6 @@ module.exports = {
   newAddress,
   getStatus,
   newFunding,
-  cryptoNetwork
+  cryptoNetwork,
+  supportsBatching
 }