firebase-ios-sdk

Make GDT CCT responsive to lifecycle and package events (#3017)

* Remove the _Private header for GDTUploadCoordinator

The normal header is also private.

* Rename GDTStorage's uploader variable to uploadCoordinator

And include it in NSSecureCoding's encoding

* Track in-flight packages to ensure their expiration callbacks are called

* Make the GDTLifecycle protocol methods optional

* Make GDT CCT's prioritizer and uploader responsive to package/lifecycle events

* Style

* Update versions