Detect when bundle methods called before `initialize`?

### Body #46355 has highlighted the fact that we don't check if `initialize` has been called before other methods that rely on it have been. For example, `get_current_version`. I'm not positive we should check that, but opening this issue so I can think it through later. ### Committer - [x] I acknowledge that I am a maintainer/committer of the Apache Airflow project.