Allow using system node (#18172)

Release Notes:

- (Potentially breaking change) Zed will now use the node installed on
your $PATH (if it is more recent than v18) instead of downloading its
own. You can disable the new behavior with `{"node":
{"disable_path_lookup": true}}` in your settings. We do not yet use
system/project-local node_modules.

---------

Co-authored-by: Mikayla <mikayla@zed.dev>

crates/workspace/src/workspace.rs

@@ -556,7 +556,7 @@ pub struct AppState {
     pub workspace_store: Model<WorkspaceStore>,
     pub fs: Arc<dyn fs::Fs>,
     pub build_window_options: fn(Option<Uuid>, &mut AppContext) -> WindowOptions,
-    pub node_runtime: Arc<dyn NodeRuntime>,
+    pub node_runtime: NodeRuntime,
     pub session: Model<AppSession>,
 }
 
@@ -590,7 +590,7 @@ impl AppState {
 
     #[cfg(any(test, feature = "test-support"))]
     pub fn test(cx: &mut AppContext) -> Arc<Self> {
-        use node_runtime::FakeNodeRuntime;
+        use node_runtime::NodeRuntime;
         use session::Session;
         use settings::SettingsStore;
         use ui::Context as _;
@@ -619,7 +619,7 @@ impl AppState {
             languages,
             user_store,
             workspace_store,
-            node_runtime: FakeNodeRuntime::new(),
+            node_runtime: NodeRuntime::unavailable(),
             build_window_options: |_, _| Default::default(),
             session,
         })
@@ -4418,7 +4418,7 @@ impl Workspace {
 
     #[cfg(any(test, feature = "test-support"))]
     pub fn test_new(project: Model<Project>, cx: &mut ViewContext<Self>) -> Self {
-        use node_runtime::FakeNodeRuntime;
+        use node_runtime::NodeRuntime;
         use session::Session;
 
         let client = project.read(cx).client();
@@ -4434,7 +4434,7 @@ impl Workspace {
             user_store,
             fs: project.read(cx).fs().clone(),
             build_window_options: |_, _| Default::default(),
-            node_runtime: FakeNodeRuntime::new(),
+            node_runtime: NodeRuntime::unavailable(),
             session,
         });
         let workspace = Self::new(Default::default(), project, app_state, cx);