Add option to configure (intelligent) tips for checkouts sent via bluetooth / not created on the terminal

[francesco79]

Right now the (intelligent) tip options and its percentages settings can be selected and edited in the native sumup app. Unfortunately the configured percentages settings only apply when the checkout is created on the terminal itself (via mobile or wifi connection). For all checkouts created in the native sumup app or any custom app using this sumup-ios-sdk (via bluetooth connection to the card reader terminal) the customized tip percentages settings get overwritten by the default ones (10%, 15%, 20%). This leads to a non-uniform experience with the offered tip percentages being dependent on the connection type or the device the checkout is created on (card terminal vs. sumup-ios-sdk/sumup app). So the requested feature is that the (intelligent) tip percentages on the card terminal do not overwrite the customized tip percentages settings for checkouts sent to the card reader via bluetooth but use the customized values instead. (Or the SDK allows to customize the tip percentages settings which are offered on the card reader terminal at least; right now the SDK only provides functions to check whether tips are possible (SumUpSDK.isTipOnCardReaderAvailable) and whether default tip options should be offered to the customer on the terminal: smpCheckoutRequest.tipOnCardReaderIfAvailable = true/false)

[francesco79]

This current behaviour is confirmed by the sumup support