Replace log with tracing

Tracing is a modern replacement for the log crate that allows for
annotating log messages with the function that they come from.

Signed-off-by: John Nunley <dev@notgull.net>
Closes: #3482

src/icon.rs

@@ -118,6 +118,8 @@ impl Icon {
     /// The length of `rgba` must be divisible by 4, and `width * height` must equal
     /// `rgba.len() / 4`. Otherwise, this will return a `BadIcon` error.
     pub fn from_rgba(rgba: Vec<u8>, width: u32, height: u32) -> Result<Self, BadIcon> {
+        let _span = tracing::debug_span!("winit::Icon::from_rgba", width, height).entered();
+
         Ok(Icon {
             inner: PlatformIcon::from_rgba(rgba, width, height)?,
         })