[Feat]: Support StoreKit Testing

[KazuCocoa]

Is your feature request related to a problem? Please describe.

A user wants to do IAP testing via StoreKit without exact AppStore connection.

Describe the solution you'd like

I wonder if we can provide IAP testing env via StoreKitSession in Appium/WDA. So for example when we provide a capability, or a settings item, the session will provide IAP testing via StoreKitSession instead of real App Store connection.

StoreKitSession
https://developer.apple.com/documentation/storekittest/sktestsession

https://developer.apple.com/documentation/xcode/setting-up-storekit-testing-in-xcode

What we should do:
https://medium.com/lightricks-tech-blog/reimplementing-storekit-testing-how-objective-c-makes-reverse-engineering-easy-1ff6befe08b5 is an article to reimplement the StoreKitSession.

According to a friend of mine, this method worked in both a simulator and a real device. He implemented this way for not Appium, ordinally, but maybe it can do in Appium/WDA as well.

I need to play something and read the article well though.

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To enhance more, we may be able to re-implement some functionality with the wrapper, like SKTestSession.disableDialogs as false.

[KazuCocoa]

https://github.com/ainame/StoreKitTestingProxy is a PoC

[DanielHaimMayberg]

Any update on this feature? Hoping to test sandbox purchases with Appium on simulator