Nomic Embed Text V2 with Mixture-of-Experts (MoE) architecture

[manyoso]

• Adds MoE-based embedding model supporting multilingual embeddings.
• Selects architecture variant based on hyperparameter detection (MoE layers).
• Removes unnecessary subclass initialization checks for clarity.

https://www.nomic.ai/blog/posts/nomic-embed-text-v2

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