Override text color with stroke selection color for selected cells (#…

…3968)

Closes #3967 


![image](https://github.com/emilk/egui/assets/2380253/4aaa55bd-e6dc-4780-a9b1-14d537d10116)

crates/egui_extras/src/layout.rs

@@ -197,6 +197,11 @@ impl<'l> StripLayout<'l> {
             child_ui.set_clip_rect(clip_rect.intersect(child_ui.clip_rect()));
         }
 
+        if flags.selected {
+            let stroke_color = child_ui.style().visuals.selection.stroke.color;
+            child_ui.style_mut().visuals.override_text_color = Some(stroke_color);
+        }
+
         add_cell_contents(&mut child_ui);
         child_ui.min_rect()
     }