Replace std::unordered_map<c10::Device, c10::Device> with DeviceMap (#64393)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64393
cc pietern mrshenli pritamdamania87 zhaojuanmao satgera rohan-varma gqchen aazzolini osalpekar jiayisuse agolynski SciPioneer H-Huang mrzzd cbalioglu gcramer23
Test Plan: Imported from OSS
Reviewed By: rohan-varma
Differential Revision: D30708384
Pulled By: pbelevich
fbshipit-source-id: 1c565727e4f09cd9e560874dd90aa403470b4a97
