message: qt: improve text for open third-party tx url action
  The text for an open third-party tx URL action
  is improved by appending the host name with "Show in".
  This makes it self-explanatory what the action will do.
diff: @@ -231,7 +231,10 @@ void TransactionView::setModel(WalletModel *_model)
  {
  if (i == 0)
  contextMenu->addSeparator();
  - contextMenu->addAction(host, [this, url] { openThirdPartyTxUrl(url); });
  + /*: Transactions table context menu action to show the
  + selected transaction in a third-party block explorer.
  + %1 is a stand-in argument for the URL of the explorer. */
  + contextMenu->addAction(tr("Show in %1").arg(host), [this, url] { openThirdPartyTxUrl(url); });
  }
  }
  }
  