multi: return txns first and last indices

In this commit we introduce first and last indices for the
tranasctions returned which can be used to seek for further
transactions in a pagination style.

Signed-off-by: Abdullahi Yunus <abdoollahikbk@gmail.com>

lnwallet/interface.go

@@ -403,7 +403,8 @@ type WalletController interface {
 	// empty, transactions of all wallet accounts are returned.
 	ListTransactionDetails(startHeight, endHeight int32,
 		accountFilter string, indexOffset uint32,
-		maxTransactions uint32) ([]*TransactionDetail, error)
+		maxTransactions uint32) ([]*TransactionDetail, uint64, uint64,
+		error)
 
 	// LeaseOutput locks an output to the given ID, preventing it from being
 	// available for any future coin selection attempts. The absolute time