Quantized H Tangent function (#31031)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31031
This activation will be needed for the LSTM implementation.
Also includes the QNNPack implementation.
Test Plan: Imported from OSS
Differential Revision: D19334280
Pulled By: z-a-f
fbshipit-source-id: ae14399765a47afdf9b1e072d3967c24ff473e8d
