Add Batch tool call for calling multiple tools (#27621)

<img width="620" alt="Screenshot 2025-03-27 at 2 29 13 PM"
src="https://github.com/user-attachments/assets/dd023507-61bc-4722-a095-f65f4b6c746a"
/>

We'll iterate on the UI, but first the goal is to just get it to work at
all so we can see if it's useful in terms of getting correct output
faster.

Release Notes:

- N/A

---------

Co-authored-by: Agus Zubiaga <hi@aguz.me>

assets/settings/default.json

@@ -643,6 +643,7 @@
         "name": "Code Writer",
         "tools": {
           "bash": true,
+          "batch-tool": true,
           "copy-path": true,
           "create-file": true,
           "delete-path": true,