Add some debug logging to understand hangs in the git store's compute_snapshot (#57317)

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [ ] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- N/A

crates/project/src/git_store.rs

@@ -9144,6 +9144,8 @@ async fn compute_snapshot(
     backend: Arc<dyn GitRepository>,
     cx: &mut AsyncApp,
 ) -> Result<RepositorySnapshot> {
+    log::debug!("starting compute snapshot");
+
     let (id, work_directory_abs_path, prev_snapshot) = this.update(cx, |this, _| {
         this.paths_needing_status_update.clear();
         (
@@ -9175,6 +9177,7 @@ async fn compute_snapshot(
             }
         })
         .await?;
+    log::debug!("fetched branches, head commit, worktrees");
     let branch = branches.iter().find(|branch| branch.is_head).cloned();
     let branch_list: Arc<[Branch]> = branches.into();
 
@@ -9198,6 +9201,8 @@ async fn compute_snapshot(
         })
         .await?;
 
+    log::debug!("fetched remotes");
+
     let snapshot = this.update(cx, |this, cx| {
         let head_changed =
             branch != this.snapshot.branch || head_commit != this.snapshot.head_commit;
@@ -9257,6 +9262,7 @@ async fn compute_snapshot(
             }
         })
         .await?;
+    log::debug!("fetched statuses, diff stats, stash entries");
 
     let diff_stat_map: HashMap<&RepoPath, DiffStat> =
         diff_stats.entries.iter().map(|(p, s)| (p, *s)).collect();