Add torch.dot for complex tensors (#42745)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/42745
Test Plan: Imported from OSS
Reviewed By: izdeby
Differential Revision: D23056382
Pulled By: anjali411
fbshipit-source-id: c97f15e057095f78069844dbe0299c14104d2fce
