feat: add Prettier-only formatting support

[J3m5]

• ✨ Introduce a delegation bridge for Prettier-only formatting.

• 🧪 Add tests for formatting specific to Prettier-only file types.

• 🐛 Fix issues with nested Tokio runtime in LSP.

• 🐛 Ensure formatter activates for JSON, CSS, and Markdown file types.

• 🐛 Scope formatter selector to supported file types.

• 📝 Require Prettier-only formatting in tests.

[Copilot]

Pull request overview

This PR adds support for formatting Prettier-only file types (JSON, CSS, Markdown) through an external formatter bridge, enabling the OXC formatter to delegate formatting to Prettier for file types it doesn't natively support.

Key Changes:

• Introduced an ExternalFormatterBridge trait and implementation for delegating formatting to Prettier
• Added activation events for CSS, JSON, JSONC, and Markdown languages in VS Code extension
• Implemented detection logic to identify Prettier-only files and route them to the external formatter
• Created comprehensive test fixtures for various Prettier-supported file types

Reviewed changes

Copilot reviewed 39 out of 40 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/oxc_language_server/src/formatter/external_formatter_bridge.rs	Defines the bridge trait for external formatters with a no-op implementation
crates/oxc_format_support/src/lib.rs	Implements file type detection and config loading for Prettier-only files
crates/oxc_language_server/src/formatter/server_formatter.rs	Integrates external formatter bridge into the formatter pipeline
apps/oxfmt/src/lsp/mod.rs	Implements NAPI bridge for external formatter with Tokio runtime handling
editors/vscode/package.json	Adds activation events for newly supported languages
editors/vscode/client/tools/formatter.ts	Extends supported file extensions list
editors/vscode/tests/e2e_server_formatter.spec.ts	Adds E2E tests for Prettier-only file formatting
crates/oxc_format_support/Cargo.toml	New crate for format support utilities
Multiple fixture files	Test data for various Prettier-supported file types

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[Copilot]

The external_options field is marked as potentially dead code when the lsp-prettier feature is disabled, but it's unconditionally included in the struct. Consider making this field conditional with #[cfg(feature = \"lsp-prettier\")] to avoid including unused data in the struct.

Suggested change

	#[cfg_attr(not(feature = "lsp-prettier"), allow(dead_code))]
	#[cfg(feature = "lsp-prettier")]

[Dunqing]

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