chore: merge git crates (#5909)

Merge `git-apply` and `git-tooling` into `utils/`

codex-rs/core/src/conversation_history.rs

@@ -530,7 +530,7 @@ fn is_api_message(message: &ResponseItem) -> bool {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use codex_git_tooling::GhostCommit;
+    use codex_git::GhostCommit;
     use codex_protocol::models::ContentItem;
     use codex_protocol::models::FunctionCallOutputPayload;
     use codex_protocol::models::LocalShellAction;