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/src/elements/div.rs

@@ -1662,7 +1662,7 @@ impl Interactivity {
         window: &mut Window,
         cx: &mut App,
     ) {
-        use crate::{BorderStyle, TextAlign};
+        use crate::BorderStyle;
 
         if global_id.is_some()
             && (style.debug || style.debug_below || cx.has_global::<crate::DebugBelow>())
@@ -1685,7 +1685,7 @@ impl Interactivity {
                     .ok()
                     .and_then(|mut text| text.pop())
                 {
-                    text.paint(hitbox.origin, FONT_SIZE, TextAlign::Left, None, window, cx)
+                    text.paint(hitbox.origin, FONT_SIZE, None, None, window, cx)
                         .ok();
 
                     let text_bounds = crate::Bounds {

crates/gpui/src/elements/text.rs

@@ -415,7 +415,9 @@ impl TextLayout {
 
         let line_height = element_state.line_height;
         let mut line_origin = bounds.origin;
+
         let text_style = window.text_style();
+
         for line in &element_state.lines {
             line.paint_background(
                 line_origin,
@@ -429,7 +431,7 @@ impl TextLayout {
             line.paint(
                 line_origin,
                 line_height,
-                text_style.text_align,
+                Some(&text_style),
                 Some(bounds),
                 window,
                 cx,