Remove todo! comments (#8981)

Switching fully to normal `todo` style

Release Notes:

- N/A

crates/gpui/src/platform/test/platform.rs

@@ -126,7 +126,7 @@ impl Platform for TestPlatform {
         #[cfg(target_os = "macos")]
         return Arc::new(crate::platform::mac::MacTextSystem::new());
 
-        // todo("windows")
+        // todo(windows)
         #[cfg(target_os = "windows")]
         unimplemented!()
     }