add SingleLoadedNetSupplier (#16620)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16620
LogfiledbNetLoader loads all external input blobs into a workspace instance, we pack a shared pointer to this loaded workspace into the SingleLoadedNetSupplier.
SingleLoadedNetSupplier will pass this workspace to BlackBoxPredictor to be executed. (D13891759 is a WIP of how it all comes together)
Reviewed By: pjh5
Differential Revision: D13901467
fbshipit-source-id: 20589f898922f5f1aec50be131dad17a8c38e9b2
