Fix logging and configuration watching in LSP

[lionel-]

The LSP is currently not emitting any log messages because:

• The default log level is 'off'
• We're not watching any log level setting so it can't be changed

I've also noticed the following issues:

• The client is not sending any notifications when Quarto settings change in the frontend. So we only ever get the initial version of settings when we sync on init.

• The log level setting on the LSP side is markdown.server.log which is a remnant from copying over the Markdown LSP.

• The LSP log levels are currently "off", "debug", and "trace". I think we're missing "warn" and "error" for important user messages, and "info" for benign user messages. If we have these, then we should probably remove "off" and have the least verbose level set to "error" (this is what we do in Ark for instance).

Main fixes in this PR:

• Move log level setting to quarto.server.logLevel.
• Actually send a didChangeConfiguration notification to the LSP server when quarto settings change in the frontend.
• Watch logLevel on the LSP side so the LSP can immediately react to log level changes.
• Also send logLevel in initializationOptions so the LSP can use the level set by the user as early as possible.

Adjacent fixes and cleanups:

• Refactor log levels to take error, warn, info, debug, and trace levels.
  Set default trace level to warn.

• Add log() wrappers like logError(), logWarn(), etc, as well as logNotification() and logRequest() to log at trace level received LSP messages.

• Call the latter in message handlers. This vastly increases the coverage of LSP events at trace level, which is very valuable for debugging.

• Minor: The logger class currently emits messages via console.log, which languageserver redirects to the client when the connection is of type StdIo (see // https://github.com/microsoft/vscode-languageserver-node/blob/df56e720/server/src/node/main.ts#L262-L264). I changed this to explicitly send messages via our connection object instead, which should also work if someone needs to connect to the LSP via TCP. This will also allow us to use more accurate LSP loggers once we switch to languageclient 10 which will support LogChannelOutput on the client side (see Adopt to new vscode log output channel API microsoft/vscode-languageserver-node#1116).

[lionel-]

This should skip the format commit in blame, at least on github

[lionel-]

Don't lint unused variables prefixed with _

[lionel-]

Taking example on Biome, we've started using the just command runner in Ark and Air. I've started one here to easily update the dev Quarto extension in Code and Positron.

[juliasilge]

What I am seeing when I build from this PR is a bit confusing:

I see Quarto LSP logging coming through 🎉 but the default for this setting seems to be warning while I see even trace messages coming through. What do you think might be happening here?

Also, like I said in #753 I think the just file should be at the root with the other build and dev scripts.