[quant][graphmode] Add quantize_per_tensor.tensors (#35916)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35916
quantize_per_tensor can now accept list of tensors.
Needed for operators like LSTM and cat
Test Plan: Imported from OSS
Differential Revision: D20830388
fbshipit-source-id: 73f81cf6b7c7614ef19a73b721bc57cf33211345
