Serialize lists to comma delimited string in PaymentAccount.toJson() instead of PaymentAccount.toForm() [0.2 XMR]
This issue requests serializing lists to a comma delimited string in PaymentAccount.toJson() instead of [PaymentAccount.toForm()](https://github.com/haveno-dex/haveno/blob/130a45c99a1ae812d3c6d6d8603005a79d2cfc19/core/src/main/java/haveno/core/payment/PaymentAccount.java#L392).

The implementation should be in PaymentAccountTypeAdapter?