Defer ignored dirs scanning

crates/project/src/ignore.rs

@@ -20,6 +20,10 @@ impl IgnoreStack {
         Arc::new(Self::All)
     }
 
+    pub fn is_all(&self) -> bool {
+        matches!(self, Self::All)
+    }
+
     pub fn append(self: Arc<Self>, abs_base_path: Arc<Path>, ignore: Arc<Gitignore>) -> Arc<Self> {
         match self.as_ref() {
             IgnoreStack::All => self,