Deprecate observerMode in favor of purchasesAreCompletedBy

[JayShortway]

Changed

• Adds PurchasesAreCompletedBy enum.
• Adds PurchasesConfiguration.Builder.purchasesAreCompletedBy()
• Deprecates PurchasesConfiguration.Builder.observerMode(), with a nice ReplaceWith action.
• Adds Purchases.syncAmazonPurchase().
• Deprecates Purchases.syncObserverModeAmazonPurchase, with a nice ReplaceWith action.
• Deprecates Purchases.finishTransactions, with an okay ReplaceWith action.
• Adds API tests for PurchasesAreCompletedBy.
• Adds API tests for purchasesAreCompletedBy().
• PaywallsTester, PurchaseTester and the MagicWeather samples use purchasesAreCompletedBy() instead of observerMode().
• Adds some unit tests for purchasesAreCompletedBy().

Not changed

This PR does not remove all internal mentions of the terms "observer mode" and "finish transactions" from the codebase. Will do that in a follow-up.

Blockers

• [x] Get consensus that this is the route we want to take.
  • [x] Enum instead of boolean? 👉 enum
  • [x] Deprecate or remove straight away? 👉 deprecate
  • [x] Decide on a target branch (8.0.0-dev or main). 👉 main
• [x] Wait for /finishing-transactions to go live, as it is mentioned in the Magic Weather samples. See https://github.com/RevenueCat/docusaurus/pull/261 👉 moved to another PR: https://github.com/RevenueCat/purchases-android/pull/1721

[RevenueCat-Danger-Bot]

	1 Message
:book:	Size increase: 10.48 KB

Generated by :no_entry_sign: Danger

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 83.10%. Comparing base (33a4377) to head (6a9026c). Report is 7 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1708 +/- ## ========================================== + Coverage 83.07% 83.10% +0.02% ========================================== Files 222 223 +1 Lines 7581 7592 +11 Branches 1073 1075 +2 ========================================== + Hits 6298 6309 +11 Misses 857 857 Partials 426 426 ```

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