message: Expose styling types for `checkbox` in `iced_web`
diff: //! Show toggle controls using checkboxes.
  -use crate::{Bus, Color, Css, Element, Widget};
  +use crate::{Bus, Css, Element, Length, Widget};
  +
  +pub use iced_style::checkbox::{Style, StyleSheet};
  use dodrio::bumpalo;
  use std::rc::Rc;
  @@ -26,7 +28,8 @@ pub struct Checkbox<Message> {
  is_checked: bool,
  on_toggle: Rc<dyn Fn(bool) -> Message>,
  label: String,
  - label_color: Option<Color>,
  + width: Length,
  + style: Box<dyn StyleSheet>,
  }
  impl<Message> Checkbox<Message> {
  @@ -48,15 +51,24 @@ impl<Message> Checkbox<Message> {
  is_checked,
  on_toggle: Rc::new(f),
  label: String::from(label),
  - label_color: None,
  + width: Length::Shrink,
  + style: Default::default(),
  }
  }
  - /// Sets the color of the label of the [`Checkbox`].
  + /// Sets the width of the [`Checkbox`].
  ///
  /// [`Checkbox`]: struct.Checkbox.html
  - pub fn label_color<C: Into<Color>>(mut self, color: C) -> Self {
  - self.label_color = Some(color.into());
  + pub fn width(mut self, width: Length) -> Self {
  + self.width = width;
  + self
  + }
  +
  + /// Sets the style of the [`Checkbox`].
  + ///
  + /// [`Checkbox`]: struct.Checkbox.html
  + pub fn style(mut self, style: impl Into<Box<dyn StyleSheet>>) -> Self {
  + self.style = style.into();
  self
  }
  }
  @@ -79,7 +91,8 @@ where
  let on_toggle = self.on_toggle.clone();
  let is_checked = self.is_checked;
  - // TODO: Complete styling
  + // TODO: Styling
  +
  label(bump)
  .children(vec![
  input(bump)
  