Allow working with different storage during export

Motivation

With 📌 Add support for config ignore Active we want to support config_ignore. Throwing the config-export event makes sense in our case, but what we need to transform is not the sync-storage, but the custom storage.

Proposed resolution

Optionally, allow other storage objects to be transformed. For example extend the event with an optional "transformation source storage" - the configuration storage object which is the source of the transformation.