Writing out the logic into the user project's source controlled Podfile means we're locking the interpretation of .flutter-plugins which is ephemeral with the Flutter tools in time and it's no longer upgradable.

Since we know we're moving the .flutter-plugins content to support federated plugins (@amirh) we should make sure the users with existing projects can handle changes in the way .flutter-plugins is written to.

cc @zanderso @jmagman