Present toast after publishing an edit, IF a new temporary account was spun up:
- (In EditSaveViewController.swift) Before publishing the edit, call WMFAuthenticationManager's `user(siteURL: URL)` method. Pass in the article URL that the user is editing as a parameter. This will return a `WMFCurrentUser` value with an `authState` property of `ip`, `temporary` or `permanent`. Make a note of this value (note, calling this method upon landing on the publish screen will likely already be done as a part of T374013).
- (In EditSaveViewController.swift) After edit publish is successful (in `handleEditSuccess`), check WMFAuthenticationManager's `user(siteURL: URL)` method again. If this second check indicates an authState of `temporary`, and the first check indicated `ip`, then we know a new temporary account was spun up during editing. Pass this flag along to the delegate when calling `self.delegate?.editSaveViewControllerDidSave(self, result: result)` in `handleEditSuccess`.
- In EditorViewController's `EditSaveViewControllerDelegate` conformance (`editSaveViewControllerDidSave`), continue passing the new flag along to the `delegate?.editorDidFinishEditing(self, result: result)` call.
- In ArticleViewController's `EditorViewControllerDelegate` conformance (`editorDidFinishEditing`), check the new flag. If flag indicates that a new temporary account was spun up, present a toast using WMFAlertManager.