This new element will let us react to click events on arbitrary ranges
of some rendered text, e.g.:
```rs
InteractiveText::new(
"element-id",
StyledText::new("Hello world, how is it going?").with_runs(vec![
cx.text_style().to_run(6),
TextRun {
background_color: Some(green()),
..cx.text_style().to_run(5)
},
cx.text_style().to_run(18),
]),
)
.on_click(vec![2..4, 1..3, 7..9], |range_ix, cx| {
println!("Clicked range {range_ix}");
})
```
As part of this, I also added the ability to give text runs a background
color.
Release Notes:
- N/A
510320bb47