Add GPT Neox Policy

[abhilash1910]

Add policy for GPT Neox

• Addresses : https://github.com/tunib-ai/parallelformers/issues/34

Description

• Change to add Neox policy consolidated with HF NeoxPretrainedModel

Linked Issues

• Addresses: https://github.com/tunib-ai/parallelformers/issues/34

[abhilash1910]

@hyunwoongko requesting review .

[abhilash1910]

Hi @sooftware , could you please let me know if this integration suffices to be added for Neox policy? The tests seem fine on Neox. Thanks.