Expose semantic token command type

Suggestion

🔍 Search Terms

language server protocol, semantic tokens, full, range, syntax highlight,

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

Hi. I'd like to get the LSP equivalent of textDocument/semanticTokens, which the Typescript codebase seems to call getSemanticTokens(), but it doesn't look like that's an available command type.

📃 Motivating Example

{"seq":1,"type":"request","command":"getSemanticTokens","arguments":{"file":"/home/user/example.ts"}}

💻 Use Cases

I'd like to have tsserver send me tokens so that I can do syntax highlighting without my editor having to understand JS/TS/etc.

See-also: https://github.com/christianbundy/lsp-editor

Start with lib/protocol.d.ts and the existing getSemanticTokens() entry point mentioned in the issue. Compare the requested textDocument/semanticTokens equivalent with the example tsserver request, then verify that the command type and request shape are exposed for editor clients.