Add Cohere and Cohere2 to KerasHub

[harshaljanjani]

Good day, I wanted to know if I could take up Cohere and Cohere2 as my next two models to integrate into KH. The Command series' performance is recognized in the top models at https://lmarena.ai/ as well, which hopefully proves relevant traction for the models, and the value it would add by having them in KerasHub.

Performance Stats: https://cohere.com/blog/command-a (March 2025) Transformers Code: https://huggingface.co/docs/transformers/en/model_doc/cohere2 https://huggingface.co/docs/transformers/en/model_doc/cohere