Change StorageImpl to track byte count rather than element count (#37776)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37776
* Remove type-specific size tracking in favor of byte size tracking in Storage and StorageImpl
* Changed numel() and set_numel() to nbytes() and set_nbytes()
* Added enum argument to Storage/StorageImpl constructor to indicate new meaning of the size parameter
* Update all callers of the changed API
Part of issue https://github.com/pytorch/pytorch/issues/33950
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37028
Differential Revision: D21171334
Pulled By: ezyang
fbshipit-source-id: 37329a379de9a3a83cc5e9007e455a3e1c2d10b8
