Add support for Microsoft Phi-3 model to DeepSpeed-FastGen

[adk9]

This PR adds support for Microsoft Phi-3 model to FastGen.

DeepSpeed-FastGen output with prompt "DeepSpeed is":

an AI-powered platform designed to optimize and scale distributed deep learning models across clusters.**

DeepSpeed is a cutting-edge AI-driven toolkit that empowers users to enhance and scale deep learning models across distributed computing environments. By harnessing the power of artificial intelligence, DeepSpeed provides innovative solutions for optimizing resource allocation, managing data synchronization, and improving model parallelism. This enables efficient scaling and execution of complex deep learning tasks, unlocking the full potential of distributed computing systems.

### Key Features of DeepSpeed:

1.