feat(remote-dev): Remote Development in the project popup, opened in a new or this window

- The title bar project popup lists Remote Development… next to Open… and Clone Repository….
- Opening a remote project follows "Open project in" (new window / this window / ask) when this window already has a project, and confirms leaving the current one first.
- A remote project already open in another window focuses that window.
- A new window connects to the host itself and shows the connection progress on its welcome screen.
- Recent remote projects get Open in New Window.

src-tauri/src/remote_dev.rs

@@ -47,6 +47,16 @@ impl Connections {
         self.0.lock().get(window).cloned()
     }
 
+    /// The window connected to folder `root` on the host of SSH configuration `ssh_config`.
+    pub fn window_of(&self, ssh_config: &str, root: &str) -> Option<String> {
+        let root = root.trim_end_matches('/');
+        self.0
+            .lock()
+            .iter()
+            .find(|(_, c)| c.ssh_config == ssh_config && c.root.trim_end_matches('/') == root)
+            .map(|(label, _)| label.clone())
+    }
+
     pub fn disconnect(&self, window: &str) {
         if let Some(c) = self.0.lock().remove(window) {
             c.peer.kill();