Use the user from the CloudUserStore to drive the user menu (#35375)

This PR updates the user menu in the title bar to base the "signed in"
state on the user in the `CloudUserStore` rather than the `UserStore`.

This makes it possible to be signed-in—at least, as far as the user menu
is concerned—even when disconnected from Collab.

Release Notes:

- N/A

crates/client/src/client.rs

@@ -1491,6 +1491,7 @@ impl Client {
 
     pub async fn sign_out(self: &Arc<Self>, cx: &AsyncApp) {
         self.state.write().credentials = None;
+        self.cloud_client.clear_credentials();
         self.disconnect(cx);
 
         if self.has_credentials(cx).await {

crates/client/src/cloud/user_store.rs

@@ -7,35 +7,56 @@ use gpui::{Context, Task};
 use util::{ResultExt as _, maybe};
 
 pub struct CloudUserStore {
-    authenticated_user: Option<AuthenticatedUser>,
-    _fetch_authenticated_user_task: Task<()>,
+    authenticated_user: Option<Arc<AuthenticatedUser>>,
+    _maintain_authenticated_user_task: Task<()>,
 }
 
 impl CloudUserStore {
     pub fn new(cloud_client: Arc<CloudApiClient>, cx: &mut Context<Self>) -> Self {
         Self {
             authenticated_user: None,
-            _fetch_authenticated_user_task: cx.spawn(async move |this, cx| {
+            _maintain_authenticated_user_task: cx.spawn(async move |this, cx| {
                 maybe!(async move {
                     loop {
+                        let Some(this) = this.upgrade() else {
+                            return anyhow::Ok(());
+                        };
+
                         if cloud_client.has_credentials() {
-                            break;
+                            if let Some(response) = cloud_client
+                                .get_authenticated_user()
+                                .await
+                                .context("failed to fetch authenticated user")
+                                .log_err()
+                            {
+                                this.update(cx, |this, _cx| {
+                                    this.authenticated_user = Some(Arc::new(response.user));
+                                })
+                                .ok();
+                            }
+                        } else {
+                            this.update(cx, |this, _cx| {
+                                this.authenticated_user = None;
+                            })
+                            .ok();
                         }
 
                         cx.background_executor()
                             .timer(Duration::from_millis(100))
                             .await;
                     }
-
-                    let response = cloud_client.get_authenticated_user().await?;
-                    this.update(cx, |this, _cx| {
-                        this.authenticated_user = Some(response.user);
-                    })
                 })
                 .await
-                .context("failed to fetch authenticated user")
                 .log_err();
             }),
         }
     }
+
+    pub fn is_authenticated(&self) -> bool {
+        self.authenticated_user.is_some()
+    }
+
+    pub fn authenticated_user(&self) -> Option<Arc<AuthenticatedUser>> {
+        self.authenticated_user.clone()
+    }
 }