Route extension logs through the BrightScript Extension output channel

[chrisdp]

Summary

• Adds src/extensionLogger.ts, a shared logger (built on @rokucommunity/logger) that writes to the developer console and to the existing BrightScript Extension output channel. The channel is already piped into the optional brightscript.extensionLogfilePath setting, so file logging works without further wiring.
• Migrates LanguageServerManager as a proof of concept: console.log/console.error → logger.info/logger.error, plus a LanguageServerManager-prefixed sub-logger so messages are tagged in the output channel.

Motivation

End-users currently can't see extension logs — the ~60 console.* calls scattered across the source only surface in the Extension Host devtools. This PR puts the plumbing in place so we can move those call sites over without each one needing to know about the output channel.

Why a draft / what's not here

Posting this for maintainer feedback on the approach before doing the wider sweep. Specifically:

• Is @rokucommunity/logger the right backbone, or should this use a LogOutputChannel (VS Code's built-in level-aware channel) instead?
• Should there be a brightscript.logLevel setting to control verbosity?
• Naming — extensionLogger.ts vs putting it on util vs something else?

If the approach is good, the follow-up is a mechanical migration of the remaining ~55 console.* calls across BrightScriptCommands, DebugConfigurationProvider, DeclarationProvider, LogOutputManager, etc.

[TwitchBronBron]

BrighterScript and roku-debug both call this file logging.ts, let's standardize on that.