gpui: Fix text hover & active style (#24723)

Release Notes:

- N/A

---

Fix this long-standing issue so that we can support Link hover colors.

And renamed `text_layout` example to `text_style`.

---

I spent some time studying the process of this text style change and
found it a bit complicated.

At first, I thought there was a problem with refine and it was not
passed properly. After changing it, I found that it was not the problem.

Then I found that it was because `TextRun` had already stored the
`color`, `background`, `underline`, `strikethrough` in TextRun in the
`request_layout` stage. They area calculate at the `request_layout`
stage, but request_layout stage there was no `hitbox`, so the hover
state was not obtained.

```bash
cargo run -p gpui --example text_style
```


https://github.com/user-attachments/assets/24f88f73-775e-41d3-a502-75a7a39ac82b

---------

Co-authored-by: Mikayla Maki <mikayla.c.maki@gmail.com>

crates/gpui/examples/text_style.rs

@@ -8,11 +8,13 @@ struct HelloWorld {}
 impl Render for HelloWorld {
     fn render(&mut self, _window: &mut Window, _cx: &mut Context<Self>) -> impl IntoElement {
         div()
+            .font_family(".SystemUIFont")
             .bg(gpui::white())
             .flex()
             .flex_col()
             .gap_2()
             .p_4()
+            .gap_4()
             .size_full()
             .child(div().child("Text left"))
             .child(div().text_center().child("Text center"))
@@ -71,6 +73,24 @@ impl Render for HelloWorld {
                             .child("100%"),
                     ),
             )
+            .child(
+                div()
+                    .id("Text Link")
+                    .text_color(gpui::blue())
+                    .cursor_pointer()
+                    .active(|this| {
+                        this.text_color(gpui::white())
+                            .bg(gpui::blue())
+                            .text_decoration_1()
+                            .text_decoration_wavy()
+                    })
+                    .hover(|this| {
+                        this.text_color(gpui::rgb(0x973717))
+                            .bg(gpui::yellow())
+                            .text_decoration_1()
+                    })
+                    .child("Text with hover, active styles"),
+            )
     }
 }