[Pipeline Refactor][Text Generation][Continuous Batching] Integration

[dsikka]

Summary

• Integrates the ContinuousBatchingScheduler with the TextGeneration Pipeline
• This requires updating the NLEngineOperator such that batches greater than size 1 can be handled. Specifically includes updating the input/output schema to include split/join methods required by the ContinuousBatchingScheduler and update the run method such that inputs can be handled by any scheduler
• Refactors the join/split functionality such that instead of launching individual threads for each SPLIT node, poll to identify the operator that is currently finished running and schedules the next operator in its split route, until all the operators within each sub graph (i.e. split route) have finished running. This is done through the help of a dataclass SplitRoute

Testing

• Tested with ORT and Deepsparse Engine + External kv_Cache. For internal kv_cache, the normal scheduler is used.
• Stills need more vigorous unit testing

[dbogunowicz]

Conditional approval -> please run the relevant integration/unit tests before landing