git: Migrate some panel code away from visible_entries (#23251)

To prepare for the introduction of folding in the git panel, these
codepaths need to work with the canonical source of all git status
entries, not just the ones that are visible in the panel.

Release Notes:

- N/A

---------

Co-authored-by: Nate <nate@zed.dev>

crates/worktree/src/worktree.rs

@@ -227,6 +227,10 @@ impl RepositoryEntry {
         self.statuses_by_path.iter().cloned()
     }
 
+    pub fn status_len(&self) -> usize {
+        self.statuses_by_path.summary().item_summary.count
+    }
+
     pub fn status_for_path(&self, path: &RepoPath) -> Option<StatusEntry> {
         self.statuses_by_path
             .get(&PathKey(path.0.clone()), &())
@@ -5718,7 +5722,7 @@ impl<'a> GitTraversal<'a> {
             if statuses.seek_forward(&PathTarget::Path(repo_path.as_ref()), Bias::Left, &()) {
                 self.current_entry_summary = Some(statuses.item().unwrap().status.into());
             } else {
-                self.current_entry_summary = Some(GitSummary::zero(&()));
+                self.current_entry_summary = Some(GitSummary::UNCHANGED);
             }
         }
     }
@@ -5755,7 +5759,7 @@ impl<'a> GitTraversal<'a> {
 
     pub fn entry(&self) -> Option<GitEntryRef<'a>> {
         let entry = self.traversal.cursor.item()?;
-        let git_summary = self.current_entry_summary.unwrap_or_default();
+        let git_summary = self.current_entry_summary.unwrap_or(GitSummary::UNCHANGED);
         Some(GitEntryRef { entry, git_summary })
     }
 }