ssh remote: Handle disconnect on project and show overlay (#19014)

Demo:



https://github.com/user-attachments/assets/e5edf8f3-8c15-482e-a792-6eb619f83de4


Release Notes:

- N/A

---------

Co-authored-by: Bennet <bennet@zed.dev>

crates/project/src/lsp_store.rs

@@ -647,17 +647,10 @@ pub struct FormattableBuffer {
 }
 
 pub struct RemoteLspStore {
-    upstream_client: AnyProtoClient,
+    upstream_client: Option<AnyProtoClient>,
     upstream_project_id: u64,
 }
 
-impl RemoteLspStore {}
-
-// pub struct SshLspStore {
-//     upstream_client: AnyProtoClient,
-//     current_lsp_settings: HashMap<LanguageServerName, LspSettings>,
-// }
-
 #[allow(clippy::large_enum_variant)]
 pub enum LspStoreMode {
     Local(LocalLspStore),   // ssh host and collab host
@@ -808,10 +801,15 @@ impl LspStore {
     pub fn upstream_client(&self) -> Option<(AnyProtoClient, u64)> {
         match &self.mode {
             LspStoreMode::Remote(RemoteLspStore {
-                upstream_client,
+                upstream_client: Some(upstream_client),
                 upstream_project_id,
                 ..
             }) => Some((upstream_client.clone(), *upstream_project_id)),
+
+            LspStoreMode::Remote(RemoteLspStore {
+                upstream_client: None,
+                ..
+            }) => None,
             LspStoreMode::Local(_) => None,
         }
     }
@@ -924,7 +922,7 @@ impl LspStore {
 
         Self {
             mode: LspStoreMode::Remote(RemoteLspStore {
-                upstream_client,
+                upstream_client: Some(upstream_client),
                 upstream_project_id: project_id,
             }),
             downstream_client: None,
@@ -3099,6 +3097,15 @@ impl LspStore {
         self.downstream_client.take();
     }
 
+    pub fn disconnected_from_ssh_remote(&mut self) {
+        if let LspStoreMode::Remote(RemoteLspStore {
+            upstream_client, ..
+        }) = &mut self.mode
+        {
+            upstream_client.take();
+        }
+    }
+
     pub(crate) fn set_language_server_statuses_from_proto(
         &mut self,
         language_servers: Vec<proto::LanguageServer>,