Added stacked quantization with RMS and SiLU fusion (#4487)

Summary:
Pull Request resolved: #4487

X-link: facebookresearch/FBGEMM#1544

Reviewed By: jiawenliu64

Differential Revision: D78111708

fbshipit-source-id: a880645b1b15509104a82a29728558ca6e564cbb

Author: Tianyu Liang