add an option to generate qrcode without amount

[canoziia]

Hello, some wallets don't support the address format:

BTCPayServer.Plugins.USDt/BTCPayServer.Plugins.USDt/Services/Payments/TronUSDtPaymentLinkExtension.cs

Line 15 in fc6a04f

return $"{prompt.Destination}?amount={due.ToString(CultureInfo.InvariantCulture)}";

Can you add an option to allow this plugin generating qrcode without amount param?