project_panel: Fix the confusing display when files or directories have the same name in a case-insensitive comparison (#19211)

- Closes #18851

Release Notes:

- Fixed directory name comparison on Linux not considering the case
([#18851](https://github.com/zed-industries/zed/issues/18851))

crates/util/src/util.rs

@@ -659,15 +659,22 @@ impl<'a> NumericPrefixWithSuffix<'a> {
         Self(prefix, remainder)
     }
 }
+
+/// When dealing with equality, we need to consider the case of the strings to achieve strict equality
+/// to handle cases like "a" < "A" instead of "a" == "A".
 impl Ord for NumericPrefixWithSuffix<'_> {
     fn cmp(&self, other: &Self) -> Ordering {
         match (self.0, other.0) {
-            (None, None) => UniCase::new(self.1).cmp(&UniCase::new(other.1)),
+            (None, None) => UniCase::new(self.1)
+                .cmp(&UniCase::new(other.1))
+                .then_with(|| self.1.cmp(other.1).reverse()),
             (None, Some(_)) => Ordering::Greater,
             (Some(_), None) => Ordering::Less,
-            (Some(a), Some(b)) => a
-                .cmp(&b)
-                .then_with(|| UniCase::new(self.1).cmp(&UniCase::new(other.1))),
+            (Some(a), Some(b)) => a.cmp(&b).then_with(|| {
+                UniCase::new(self.1)
+                    .cmp(&UniCase::new(other.1))
+                    .then_with(|| self.1.cmp(other.1).reverse())
+            }),
         }
     }
 }