refactor(auth): introduce _ensureUserDataExists to handle default doc…#20

fulleni merged 1 commit intomainflutter-news-app-full-source-code/flutter-news-app-api-server-full-source-code:mainfrom

fix_new_user_unprepared_settings_and_preferencesflutter-news-app-full-source-code/flutter-news-app-api-server-full-source-code:fix_new_user_unprepared_settings_and_preferencesCopy head branch name to clipboard