feat(firebase_analytics): add `logInAppPurchase` support for iOS #2087

Job	Run time
android (tests)	13m 13s
android (packages/cloud_firestore/cloud_firestore/example)	12m 48s
android (packages/cloud_firestore/cloud_firestore/example)	45m 2s
android (tests)	11m 22s
	1h 22m 25s

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