fix: ui: Pin popups with no positioning to the initial cursor position

This avoids the floating popup following the cursor as we type.

helix-term/src/ui/popup.rs

@@ -110,8 +110,7 @@ impl<T: Component> Component for Popup<T> {
 
         let position = self
             .position
-            .or_else(|| cx.editor.cursor().0)
-            .unwrap_or_default();
+            .get_or_insert_with(|| cx.editor.cursor().0.unwrap_or_default());
 
         let (width, height) = self.size;