Allow opening the FS root dir as a remote project (#30190)

### Todo

* [x] Allow opening `ssh://username@host:/` from the CLI
* [x] Allow selecting `/` in the `open path` picker
* [x] Allow selecting the home directory in the `open path` picker

Release Notes:

- Changed the initial state of the SSH project picker to show the full
path to your home directory on the remote machine, instead of `~`.
- Added the ability to open `/` as a project folder over SSH

---------

Co-authored-by: Agus Zubiaga <hi@aguz.me>

crates/file_finder/src/open_path_prompt.rs

@@ -1,7 +1,7 @@
 use futures::channel::oneshot;
 use fuzzy::{StringMatch, StringMatchCandidate};
 use picker::{Picker, PickerDelegate};
-use project::DirectoryLister;
+use project::{DirectoryItem, DirectoryLister};
 use std::{
     path::{MAIN_SEPARATOR_STR, Path, PathBuf},
     sync::{
@@ -137,6 +137,7 @@ impl PickerDelegate for OpenPathDelegate {
         } else {
             (query, String::new())
         };
+
         if dir == "" {
             #[cfg(not(target_os = "windows"))]
             {
@@ -171,6 +172,13 @@ impl PickerDelegate for OpenPathDelegate {
                 this.update(cx, |this, _| {
                     this.delegate.directory_state = Some(match paths {
                         Ok(mut paths) => {
+                            if dir == "/" {
+                                paths.push(DirectoryItem {
+                                    is_dir: true,
+                                    path: Default::default(),
+                                });
+                            }
+
                             paths.sort_by(|a, b| compare_paths((&a.path, true), (&b.path, true)));
                             let match_candidates = paths
                                 .iter()
@@ -309,12 +317,16 @@ impl PickerDelegate for OpenPathDelegate {
         let Some(candidate) = directory_state.match_candidates.get(*m) else {
             return;
         };
-        let result = Path::new(
-            self.lister
-                .resolve_tilde(&directory_state.path, cx)
-                .as_ref(),
-        )
-        .join(&candidate.path.string);
+        let result = if directory_state.path == "/" && candidate.path.string.is_empty() {
+            PathBuf::from("/")
+        } else {
+            Path::new(
+                self.lister
+                    .resolve_tilde(&directory_state.path, cx)
+                    .as_ref(),
+            )
+            .join(&candidate.path.string)
+        };
         if let Some(tx) = self.tx.take() {
             tx.send(Some(vec![result])).ok();
         }
@@ -355,7 +367,11 @@ impl PickerDelegate for OpenPathDelegate {
                 .inset(true)
                 .toggle_state(selected)
                 .child(HighlightedLabel::new(
-                    candidate.path.string.clone(),
+                    if directory_state.path == "/" {
+                        format!("/{}", candidate.path.string)
+                    } else {
+                        candidate.path.string.clone()
+                    },
                     highlight_positions,
                 )),
         )