Replace `tracing` log functions in `ruff server` with LSP-compliant logging functions

[snowsignal]

Summary

Closes https://github.com/astral-sh/ruff/issues/10968.

At the moment, the log level is always set to Info. Log level configuration will be implemented in a follow-up.

Test Plan

Add a series of logs, one for each level, to the definition of Server::new, after the logger is initialized:

You should see the following logs in the output of the VS Code extension:

[github-actions[bot]]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.

[charliermarsh]

Is there an alternate design whereby we wire up tracing to emit to the LSP client? I.e., some kind of tracing configuration that would let us continue to use tracing::info! and friends, but also emit to the client?

[MichaReiser]

@charliermarsh I think that should be possible by setting up our own subscriber that then forwards messages to the LSP.

I think the problem this approach is that it only works for ruff_server, but we will use tracing in runes too and we don't have the luxury to change all tracing calls there.

I think we need to explore an alternative approach that captures all tracing messages (subscriber) and forwards them correctly OR setup an alternative subscriber that writes e.g. to a file, although I would prefer seeing the tracing messages in vs code.

[charliermarsh]

Yeah I would prefer trying to integrate this into tracing too (for those reasons, plus it's the API I would've naturally reached for if I went to write code in the LSP as a future editor / author). @snowsignal can you give it a shot?

[snowsignal]

@charliermarsh Sure, I'll see what I can do!

[snowsignal]

This PR is really outdated, especially with the major refactors we made to server initialization. I'll re-implement this feature in a new PR that's based off of the latest main.