lsp: enable custom configs to be passed into tsgo LSP

[johnnycheng0210]

Context

Address the feat request in this ticket, by allowing custom configs to be passed to the tsgo LSP.

[johnnycheng0210]

@microsoft-github-policy-service agree company="Canva"

[Copilot]

Pull Request Overview

This PR enables custom configuration file names to be passed to the tsgo Language Server Protocol (LSP) implementation. The primary purpose is to allow users to specify alternative TypeScript configuration files (e.g., tsconfig.build.json) instead of defaulting to the standard tsconfig.json or jsconfig.json files.

Key changes include:

• Adding CustomConfigFileName field to session options for configuration file customization
• Implementing custom config file search logic with fallback to default behavior
• Integrating the custom config option through the VS Code extension settings and LSP initialization

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
internal/project/session.go	Adds CustomConfigFileName field to SessionOptions struct
internal/project/configfileregistrybuilder.go	Implements custom config file search logic with fallback to standard files
internal/lsp/server.go	Extracts custom config filename from LSP initialization options and passes to session
_extension/src/extension.ts	Updates configuration change detection to include custom config filename setting
_extension/src/client.ts	Passes custom config filename from VS Code settings to LSP initialization options
_extension/package.json	Adds VS Code setting for custom config filename configuration