Expand browser and computer use requirements (#39995)

## What changed

- Add a top-level `allow_browser_and_computer_use` requirement.
- Support browser requirements for history access, automatic review, persistent approvals, and default or per-origin access policies.
- Support computer-use requirements for persistent approvals, default app access, macOS bundle IDs, Windows AUMIDs, and Windows executables.
- Preserve these settings and their sources when composing layered requirements.

## Testing

- Cover deserialization, empty-value detection, source propagation, and layered TOML merging for the new requirements.

GitOrigin-RevId: d14a10b64465f1c54e9bcc3795dc93031e6b029b

codex-rs/core/src/config/config_tests.rs

@@ -9886,6 +9886,7 @@ async fn test_requirements_web_search_mode_allowlist_does_not_warn_when_unset()
         allow_managed_hooks_only: None,
         allow_appshots: None,
         allow_remote_control: None,
+        allow_browser_and_computer_use: None,
         computer_use: None,
         browser_use: None,
         in_app_browser: None,