Nano : add API for InferenceOptimizer and deprecated some Trainer APIs (

#5768)

* add api and deprecated

* add license

* add deprecated

* update comment for api display

* modify comment

* update based on comment

docs/readthedocs/source/doc/PythonAPI/Nano/pytorch.rst

@@ -9,6 +9,14 @@ bigdl.nano.pytorch.Trainer
     :undoc-members:
     :exclude-members: accelerator_connector, checkpoint_connector, reload_dataloaders_every_n_epochs, limit_val_batches, logger, logger_connector, state
 
+bigdl.nano.pytorch.InferenceOptimizer
+---------------------------
+
+.. autoclass:: bigdl.nano.pytorch.InferenceOptimizer
+    :members:
+    :undoc-members:
+    :exclude-members: 
+
 bigdl.nano.pytorch.TorchNano
 ---------------------------