[in_app_purchase_storekit] Group purchases into a single event in storekit2

[Hari-07]

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Fixes flutter/flutter#187355

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[gemini-code-assist]

Code Review

This pull request modifies the StoreKit 2 implementation to batch restored transactions into a single update callback instead of sending them individually. It aggregates verified transactions into an array and dispatches them together using a new sendTransactionUpdates helper method. Additionally, a unit test has been added to verify that restoring multiple products emits a single batched update. There are no review comments, and I have no feedback to provide.

[LouiseHsu]

as far as i can tell, this means that if theres even one unverified transaction, the entire batch of transactions will not be dispatched. is this the behaviour you expect? I would imagine you would want to at least dispatch the verified transactions that have already been iterated over

[Hari-07]

Yeah that makes sense, will update

[LouiseHsu]

LGTM!😊