Update Gemstsah::Logging.logger to use configured logfile

[technicalpickles]

Description:

This was hard-coded to $stdout, but should use what a user configures.

---

Tasks:

• Describe the problem / feature
• Write tests

I will abide by the code of conduct.

[technicalpickles]

I just realized now that this is being used, gemstash ends up defaulting to the server.log. That means that there is no output when running gemstash start.

If that is the case, and the logfile hasn't been used, I think it'd make sense to default log_file to stdout instead

[NathanZook]

@technicalpickles I'm seeing a bunch of failing tests. What is the status here?

[technicalpickles]

I don't recall the errors, but updating the branch from main was enough to fix it 🤷🏻