Check for outdated journal at startup

To prevent accidentally branching the repository when the journal.log became outdated (e.g. OAK-3702) we could add an additional safety feature which would prevent the repository from starting in such cases. There's a couple of concerns to address:

• What kind of tooling / guidance do we need to provide to recover should such a situation be detected?
• How do we detect the journal.log being outdated?
• How do we prevent false positives?
• How do we deal with situation where the journal.log modifications are intended (e.g. by tools, of manual interventions)?