When importing a watch-only address over `importmulti` with a specific timestamp, the wallet's `nTimeFirstKey` will be set to 1.
I think we should add a optional timestamp to `CWallet::AddWatchOnly()` and use it when importing addresses or pubkeys.

continue;
            
            
            if (nDepth == 0 && !pcoin->InMempool())
                continue;
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            if (nDepth == 0 && fOnlyConfirmed && pcoin->mapValue.count("replaces_txid")) {
                continue;
            }