Adds quantized addition and renames sum to add (#20233)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20233
Adding a quantized addition (without relu)
Reviewed By: jianyuh
Differential Revision: D15245791
fbshipit-source-id: 34ede5d805d9ab0d31e8ae87cefb110504bd3c87
