feat: missing type for batch request input and output objects

[NikkiAung]

• I understand that this repository is auto-generated and my pull request may not be merged

Changes being requested

Developed types feat req for missing type for batch request input and output objects

src/openai/types/__init__.py
src/openai/types/batch_request_input.py
src/openai/types/batch_request_output.py

Additional context & links

https://platform.openai.com/docs/api-reference/batch/request-input
https://platform.openai.com/docs/api-reference/batch/request-output

Fixed #1937

[NikkiAung]

If anyone is interested in trying this feature early using this git branch, your feedback would be greatly appreciated, @RobertCraigie, @hallacy & @rachellim. :))

Next step would be considering making url in BatchRequestInput either of below.

url: Required[BatchRequestURL]

BatchRequestURL: TypeAlias = Literal[
    "/v1/responses",
    "/v1/chat/completions",
    "/v1/embeddings",
    "/v1/completions",
    "/v1/moderations",
]

or

url: Required[str]