[quant][pyper] Make offsets an optional paramter in the qembedding_bag op (#42924)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42924
offsets is an optional paramter in the python module currently. So we update the operator to follow suit
in order to avoid bad optional access
Test Plan:
python test/test_quantization.py TestQuantizeDynamicJitOps.test_embedding_bag
Imported from OSS
Reviewed By: radkris-git
Differential Revision: D23081152
fbshipit-source-id: 847b58f826f5a18e8d4978fc4afc6f3a96dc4230
