Add Gemma

[yisi-wang-slalom]

Description of changes:

We are excited to help adding support for Gemma model architectured by Google.

A few highlights, mainly referencing: huggingface/transformers#29402

• Using gelu_new activation function, we've validated it against the PyTorch implementation of gelu_pytorch_tanh to ensure same result, and recommend implementing gelu_pytorch_tanh when possible.
• Add Layernorm (w+1) of RMS Layernorm for gemma
• Include additional normalization in embedding (multiplies the embeddings by sqrt(hidden_dim)) for gemma

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[aws-guangyhu]

As of release 2.26.0, support has ended for the Transformers NeuronX library. If you are still using Transformers NeuronX, Neuron recommends that you migrate to the NxD Inference library, which provides a PyTorch-based inference library. Refer to the migration guide to learn how to migrate your Transformers NeuronX workloads to NxD Inference. PyTorch inference Deep Learning Container (DLC) will no longer include the transformers-neuronx package as well and Neuron no longer provides the transformers_neuronx virtual environment in both single and multi-framework DLAMIs. For more details, see Announcing end of support for Transformers NeuronX library starting in Neuron 2.26 release.