Show payment method form and additional information when only only one payment method is available

[danielcivit]

I would like to suggest an improvement in the following specification; and therefore an improvement in the behavior of the checkout payment step.

https://github.com/PrestaShop/prestashop-specs/blob/master/content/1.7/front-office/checkout.md?plain=1#L35

In those cases in which the Payment Option have a form defined; or additional information defined; then that section of the payment method should be shown as well; since the payment method is selected.

• https://github.com/PrestaShop/PrestaShop/blob/1.7.8.1/src/Core/Payment/PaymentOption.php#L162-L167
• https://github.com/PrestaShop/PrestaShop/blob/1.7.8.1/src/Core/Payment/PaymentOption.php#L258-L263

Thanks in advanced for consider this suggestion.