fix: store console files in subdirectory of iroh data dir

[Frando]

Description

We used to store the console files (history and current author) in a subdirectory console under the iroh data dir. This got lost in some refacorings, and the console files currently are created in the iroh data directory directly.

This is bad because the iroh data directory is a single namespace, and we should use it cautiously.

This PR goes back to using a console subdirectory. Existing files are migrated on first start of the console.

Based on #2299 because this already made the environment init functions async.

Breaking Changes

Notes & open questions

Change checklist

• [ ] Self-review.
• [ ] Documentation updates if relevant.
• [ ] Tests if relevant.
• [ ] All breaking changes documented.