Update block diagnostics (#28006)

Release Notes:

- "Block" diagnostics (that show up in the diagnostics view, or when
using `f8`/`shift-f8`) are rendered more clearly
- `f8`/`shift-f8` now always go to the "next" or "prev" diagnostic,
regardless of the state of the editor

![Screenshot 2025-04-09 at 16 42
09](https://github.com/user-attachments/assets/ae6d2ff6-5183-4b74-89d0-fefee1aa11e3)

---------

Co-authored-by: Kirill Bulatov <mail4score@gmail.com>
Co-authored-by: Julia Ryan <juliaryan3.14@gmail.com>

crates/language/src/buffer.rs

@@ -1265,6 +1265,7 @@ impl Buffer {
         self.reload_task = Some(cx.spawn(async move |this, cx| {
             let Some((new_mtime, new_text)) = this.update(cx, |this, cx| {
                 let file = this.file.as_ref()?.as_local()?;
+
                 Some((file.disk_state().mtime(), file.load(cx)))
             })?
             else {