export SequenceBeamSearch and SamplingModule to ops package.

https://github.com/tensorflow/models/issues/10638

PiperOrigin-RevId: 448816131

official/nlp/modeling/ops/__init__.py

@@ -14,5 +14,7 @@
 
 """Ops package definition."""
 from official.nlp.modeling.ops.beam_search import sequence_beam_search
+from official.nlp.modeling.ops.beam_search import SequenceBeamSearch
+from official.nlp.modeling.ops.sampling_module import SamplingModule
 from official.nlp.modeling.ops.segment_extractor import get_next_sentence_labels
 from official.nlp.modeling.ops.segment_extractor import get_sentence_order_labels