fix data racing due to mutable reference using deepcopy

[xiezhq-hermann]

Motivation

Objects including BatchTokenIDOut and BatchEmbeddingOut hold mutable references to ongoing requests, which could cause data racing when the order of accesses are not strictly ordered.

Modifications

Using field to ensure list object is copied and deepcopy to remove all possible mutable references.

Checklist

• Format your code according to the Contributor Guide.
• Add unit tests as outlined in the Contributor Guide.
• Update documentation as needed, including docstrings or example tutorials.