[copilot] Add missing Android PR reviewer tools (#12664)

The Android PR Reviewer could not fetch external documentation or filter large diffs, contributing to agent timeout and workflow failure.

- **Tool access**
  - Enable the built-in `web-fetch` tool.
  - Allow `sed` for bounded diff inspection.
- **Generated workflow**
  - Recompile `android-reviewer.lock.yml` with the updated permissions.

- Fixes #12661

Author: Copilot

.github/workflows/android-reviewer.lock.yml

@@ -50,8 +50,10 @@ tools:
     - grep
     - head
     - jq
+    - sed
     - tail
     - wc
+  web-fetch:
   github:
     github-token: ${{ secrets.GITHUB_TOKEN }}
     toolsets: [pull_requests, repos]