Allow to pass in masks through db (#31676)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31676
Facebook：
Previously we assumed mask is passed in as a tensor which is not feasible for sparse parameter.
Here we allow to pass in the mask through db path which requires the masks to be stored in some db first.
Test Plan: unit tests
Reviewed By: ellie-wen
Differential Revision: D18928753
fbshipit-source-id: 75ca894de0f0dcd64ce17b13652484b3550cbdac
