docs: add continuous batching page (#41847)
* docs: add continuous batching page
* docs(cb): add `generate_batch` example
* docs(cb): add `opentelemtry` and `serving` section
* feat: add `TODO` note about opentelemetry dependency
* docs(cb): add supported features
* docs(cb): add unsupported features
* docs(cb): add `ContinuousBatchingManager` example
* docs(cb): x reference CB in optimizing inference
