[Model] Add LlamaEmbeddingModel as an embedding Implementation of LlamaModel

[jsato8094]

This PR adds LlamaEmbeddingModel as an embedding implementation of LlamaModel in the model registry. LlamaEmbeddingModel has already been introduced as the implementation for MistralModel, and this addition leverages the existing implementation.

Background:
At my company, we are developing an embedding model based on LlamaModel and wish to run it with vLLM. Internal tests confirm that it works as expected within our environment. However, due to company policies, we are not yet able to share further details publicly. Adding this change would be extremely helpful, as it would allow us to use our model in a more accessible way and assist in eventually making it public. Thank you for considering this request.

FIX #xxxx (link existing issues this PR will resolve)

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[github-actions]

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[DarkLight1337]

Sounds reasonable, thanks for extending this!