assistant2: Suggest current file as context (#22526)

Suggest adding the current file as context in the new assistant panel.



https://github.com/user-attachments/assets/62bc267b-3dfe-4a3b-a6af-c89af2c779a8


Note: This doesn't include suggesting the current thread in the inline
assistant.

Release Notes:

- N/A

crates/assistant2/src/ui/context_pill.rs

@@ -33,7 +33,7 @@ impl RenderOnce for ContextPill {
             px(4.)
         };
         let icon = match self.context.kind {
-            ContextKind::File => IconName::File,
+            ContextKind::File(_) => IconName::File,
             ContextKind::Directory => IconName::Folder,
             ContextKind::FetchedUrl => IconName::Globe,
             ContextKind::Thread => IconName::MessageCircle,