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/activity_indicator/src/activity_indicator.rs

@@ -205,7 +205,7 @@ impl ActivityIndicator {
                 }
                 LanguageServerBinaryStatus::Downloading => downloading.push(status.name.0.as_ref()),
                 LanguageServerBinaryStatus::Failed { .. } => failed.push(status.name.0.as_ref()),
-                LanguageServerBinaryStatus::Downloaded | LanguageServerBinaryStatus::Cached => {}
+                LanguageServerBinaryStatus::None => {}
             }
         }