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/languages/src/rust.rs

@@ -16,10 +16,9 @@ use task::{
     TaskVariables,
 };
 use util::{
-    async_maybe,
     fs::remove_matching,
     github::{latest_github_release, GitHubLspBinaryVersion},
-    ResultExt,
+    maybe, ResultExt,
 };
 
 pub struct RustLspAdapter;
@@ -397,7 +396,7 @@ impl ContextProvider for RustContextProvider {
 }
 
 async fn get_cached_server_binary(container_dir: PathBuf) -> Option<LanguageServerBinary> {
-    async_maybe!({
+    maybe!(async {
         let mut last = None;
         let mut entries = fs::read_dir(&container_dir).await?;
         while let Some(entry) = entries.next().await {