integrate int8 swish with net transformer
Summary:
add a fuse path for deq->swish->quant
update swish fake op interface to take arguments accordingly
Test Plan:
net_runner passes
unit tests need to be updated
Reviewed By: venkatacrc
Differential Revision: D22962064
fbshipit-source-id: cef79768db3c8af926fca58193d459d671321f80
