Replace Type dispatch with ATenDispatch (#21320)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21320
ghimport-source-id: cc18f746a1c74df858cb0f6d8b7d4de4315683c7
Test Plan: Imported from OSS
Differential Revision: D15637222
Pulled By: li-roy
fbshipit-source-id: fcfaea0b5480ab966175341cce92e3aa0be7e3cb
