Visual indication support for menu_image_button and ImageButton with no frame

**Describe the bug**
Currently tab doesn't show any indicator for both `menu_image_button` and `ImageButton`

**To Reproduce**
Steps to reproduce the behavior:
1. Make a new `ImageButton` e.g.
```rust
ui.add(
ImageButton::new(SizedTexture::new(
texture_id,
egui::Vec2::new(5.0, 5.0),
))
.frame(false)
)
```
2. Hit `tab` and notice that the selected element is isn't shown.

**Expected behavior**
Like other buttons an image button should show a selection indicator even without a frame

Start by locating the ImageButton and menu_image_button implementations and compare their tab-focus rendering with other buttons. Reproduce the provided frame(false) example, then verify that tab selection shows an indicator for both image-button variants without a frame.

Written by the indexing model from the issue text.