agent: Handle attempts to use hallucinated tools (#29946)

This change:

1. Catches attempts to use missing tools. If this happens, we now send
Agent a message listing available tools, after which Agent can
gracefully recover. Prior behavior: thread would stop in a broken state.

Example of a hallucinated call and a message we send back: 

![image](https://github.com/user-attachments/assets/92a8f700-b192-4038-8c7e-0a74ca2e0146)

2. Adds evals for hallucinated tool use and imagined edits
3. Adds ability to configure a profile name in evals.



Release Notes:

- N/A

crates/agent/src/active_thread.rs

@@ -1070,6 +1070,22 @@ impl ActiveThread {
                     cx,
                 );
             }
+            ThreadEvent::MissingToolUse {
+                tool_use_id,
+                ui_text,
+            } => {
+                self.render_tool_use_markdown(
+                    tool_use_id.clone(),
+                    ui_text,
+                    "",
+                    self.thread
+                        .read(cx)
+                        .output_for_tool(tool_use_id)
+                        .map(|output| output.clone().into())
+                        .unwrap_or("".into()),
+                    cx,
+                );
+            }
         }
     }