feat(core) Add login to shell_command tool (#6846)

## Summary
Adds the `login` parameter to the `shell_command` tool - optional,
defaults to true.

## Testing
- [x] Tested locally

codex-rs/core/tests/suite/mod.rs

@@ -46,6 +46,7 @@ mod review;
 mod rmcp_client;
 mod rollout_list_find;
 mod seatbelt;
+mod shell_command;
 mod shell_serialization;
 mod stream_error_allows_next_turn;
 mod stream_no_completed;