Fix tp worker only checking req[0] for stream

[Qubitium]

One condition of early exiting the decoding batch (fixed 10 size) loop is to check if batch contains streaming requests.

Fix the current code in tp_worker which only checks the first request self.running_batch.reqs[0].stream and use a new Batch.has_stream(self) -> bool helper function to check if any batch.req has stream == true.

TESTS:

• PASSED Mixed stream + non-stream + tp=2