Allow reviewing of agent changes without Git (#27668)

Release Notes:

- N/A

crates/assistant2/src/assistant.rs

@@ -1,5 +1,6 @@
 mod active_thread;
 mod assistant_configuration;
+mod assistant_diff;
 mod assistant_model_selector;
 mod assistant_panel;
 mod buffer_codegen;
@@ -37,6 +38,7 @@ pub use crate::assistant_panel::{AssistantPanel, ConcreteAssistantPanelDelegate}
 pub use crate::inline_assistant::InlineAssistant;
 pub use crate::thread::{Message, RequestKind, Thread, ThreadEvent};
 pub use crate::thread_store::ThreadStore;
+pub use assistant_diff::AssistantDiff;
 
 actions!(
     assistant2,
@@ -61,7 +63,9 @@ actions!(
         FocusRight,
         RemoveFocusedContext,
         AcceptSuggestedContext,
-        OpenActiveThreadAsMarkdown
+        OpenActiveThreadAsMarkdown,
+        ToggleKeep,
+        Reject
     ]
 );