[Winback] Apply Apple API for subscription cancellation

[danielebogo]

📘 Part of: #2435

Fixes #2444
Fixes #2445

This PR uses the StorerKit.AppStore API to present the subscriptions panel and handle those

To test

• CI must be 🟢
• Make sure you enabled winback FF
• Use a real device with a sandbox account
• Use a Plus/Patron account or a free account and purchase a Plan
• Got to your account, Cancel Subscription
• Tap on Continue to Cancellation
• On the new screen tap on Yes, Cancel my Subscription
• You should see the Apple screen to manage the sunscription
• Tap on cancel the subscriptions
• Dismiss the view
• Now, the API to check the receipt may take some times. I need to investigate if we can get the new status quickly. If the state doesn't reload try to force reload your account till the new status updates

Checklist

• I have considered if this change warrants user-facing release notes and have added them to CHANGELOG.md if necessary.
• I have considered adding unit tests for my changes.
• I have updated (or requested that someone edit) the spreadsheet to reflect any new or changed analytics.

[dangermattic]

	2 Warnings
⚠️	View files have been modified, but no screenshot or video is included in the pull request. Consider adding some for clarity.
⚠️	This PR is assigned to the milestone 7.78. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

Generated by 🚫 Danger

[SergioEstevao]

Could this code to be refactored to a separated function that could part of IAPHelper in order to better contain any StoreKit code?

[danielebogo]

@SergioEstevao I part of it to the IAPHandler. All the part related to the groupID and StoreKit, so now everything is well decoupled

[SergioEstevao]

Functionality wise is working correctly, just asked for a code change.

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✅ danielebogo
❌ Daniele Bogo

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[SergioEstevao]

Thanks for addressing the suggestion!