Fix issues with extension API that come up when moving Svelte into an extension (#9611)

We're doing it. Svelte support is moving into an extension. This PR
fixes some issues that came up along the way.

Notes

* extensions need to be able to retrieve the path the `node` binary
installed by Zed
* previously we were silently swallowing any errors that occurred while
loading a grammar
* npm commands ran by extensions weren't run in the right directory
* Tree-sitter's WASM stdlib didn't support a C function (`strncmp`)
needed by the Svelte parser's external scanner
* the way that LSP installation status was reported was unnecessarily
complex

Release Notes:

- Removed built-in support for the Svelte and Gleam languages, because
full support for those languages is now available via extensions. These
extensions will be suggested for download when you open a `.svelte` or
`.gleam` file.

---------

Co-authored-by: Marshall <marshall@zed.dev>

crates/workspace/src/notifications.rs

@@ -184,7 +184,7 @@ impl LanguageServerPrompt {
     }
 
     async fn select_option(this: View<Self>, ix: usize, mut cx: AsyncWindowContext) {
-        util::async_maybe!({
+        util::maybe!(async move {
             let potential_future = this.update(&mut cx, |this, _| {
                 this.request.take().map(|request| request.respond(ix))
             });