Pass new transactions to the event stream

- When a proposal is correct and new transactions are prepared to be submitted, we're letting know clients about those asap.

Sources/ZcashLightClientKit/Synchronizer.swift

@@ -72,7 +72,7 @@ public enum SynchronizerEvent {
     case minedTransaction(ZcashTransaction.Overview)
 
     // Sent when the synchronizer finds a mined transaction
-    case foundTransactions(_ transactions: [ZcashTransaction.Overview], _ inRange: CompactBlockRange)
+    case foundTransactions(_ transactions: [ZcashTransaction.Overview], _ inRange: CompactBlockRange?)
     // Sent when the synchronizer fetched utxos from lightwalletd attempted to store them.
     case storedUTXOs(_ inserted: [UnspentTransactionOutputEntity], _ skipped: [UnspentTransactionOutputEntity])
     // Connection state to LightwalletEndpoint changed.

Sources/ZcashLightClientKit/Synchronizer/SDKSynchronizer.swift

@@ -379,6 +379,9 @@ public class SDKSynchronizer: Synchronizer {
         var iterator = transactions.makeIterator()
         var submitFailed = false
 
+        // let clients know the transaction repository changed
+        eventSubject.send(.foundTransactions(transactions, nil))
+        
         return AsyncThrowingStream() {
             guard let transaction = iterator.next() else { return nil }