Maintain selection on file/dir deletion in project panel (#20577)

Closes #20444

- Focus on next file/dir on deletion.
- Focus on prev file/dir in case where it's last item in worktree.
- Tested when multiple files/dirs are being deleted.

Release Notes:

- Maintain selection on file/dir deletion in project panel.

---------

Co-authored-by: Kirill Bulatov <kirill@zed.dev>

crates/util/src/paths.rs

@@ -378,7 +378,15 @@ pub fn compare_paths(
                         .as_deref()
                         .map(NumericPrefixWithSuffix::from_numeric_prefixed_str);
 
-                    num_and_remainder_a.cmp(&num_and_remainder_b)
+                    num_and_remainder_a.cmp(&num_and_remainder_b).then_with(|| {
+                        if a_is_file && b_is_file {
+                            let ext_a = path_a.extension().unwrap_or_default();
+                            let ext_b = path_b.extension().unwrap_or_default();
+                            ext_a.cmp(ext_b)
+                        } else {
+                            cmp::Ordering::Equal
+                        }
+                    })
                 });
                 if !ordering.is_eq() {
                     return ordering;
@@ -433,6 +441,28 @@ mod tests {
         );
     }
 
+    #[test]
+    fn compare_paths_with_same_name_different_extensions() {
+        let mut paths = vec![
+            (Path::new("test_dirs/file.rs"), true),
+            (Path::new("test_dirs/file.txt"), true),
+            (Path::new("test_dirs/file.md"), true),
+            (Path::new("test_dirs/file"), true),
+            (Path::new("test_dirs/file.a"), true),
+        ];
+        paths.sort_by(|&a, &b| compare_paths(a, b));
+        assert_eq!(
+            paths,
+            vec![
+                (Path::new("test_dirs/file"), true),
+                (Path::new("test_dirs/file.a"), true),
+                (Path::new("test_dirs/file.md"), true),
+                (Path::new("test_dirs/file.rs"), true),
+                (Path::new("test_dirs/file.txt"), true),
+            ]
+        );
+    }
+
     #[test]
     fn compare_paths_case_semi_sensitive() {
         let mut paths = vec![