This function is used to do payment using custom UI. It takes "CustomUI" as an argument,
which consists of the brand name, checkout id, card number, holder name, month, year and cvv.
The function returns a Future of PaymentResultData.
This function allows the user to make payments using their stored cards.
It accepts an argument of type StoredCards and makes a call to the implementPaymentStoredCards
function with the values required for the payment.
It returns a Future
This async function takes a ReadyUI object as input and returns a Future object of type PaymentResultData.
It implements a payment operation by passing the Brand name, Checkout ID, Shopper Result URL,
Payment Channel name, Payment mode, Language, Theme color in HEX (iOS),
and a flag to set the store payment details mode.
The function waits for the payment operation to complete and returns the resulting PaymentResultData.