Introduce primitives in GitStore to support reviewing assistant diffs (#27576)

Release Notes:

- N/A

crates/git_ui/src/git_panel.rs

@@ -2259,7 +2259,7 @@ impl GitPanel {
 
         let repo = repo.read(cx);
 
-        for entry in repo.status() {
+        for entry in repo.cached_status() {
             let is_conflict = repo.has_conflict(&entry.repo_path);
             let is_new = entry.status.is_created();
             let staging = entry.status.staging();

crates/git_ui/src/project_diff.rs

@@ -339,7 +339,7 @@ impl ProjectDiff {
 
         let mut result = vec![];
         repo.update(cx, |repo, cx| {
-            for entry in repo.status() {
+            for entry in repo.cached_status() {
                 if !entry.status.has_changes() {
                     continue;
                 }