Add initial implementation for Cohere provider support

[ystoneman]

💻 变更类型 | Change Type

• ✨ feat
• 🐛 fix
• ♻️ refactor
• 💄 style
• 🔨 chore
• ⚡️ perf
• 📝 docs

🔀 变更说明 | Description of Change

#2068 -- Adding support for Cohere as a model provider.

📝 补充信息 | Additional Information

This is a work in progress.

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[arvinxx]

@ystoneman hi~ plz rebase the main

[kele527]

这个pr 还会考虑合入吗？

[lobehubbot]

Bot detected the issue body's language is not English, translate it automatically. 👯👭🏻🧑‍🤝‍🧑👫🧑🏿‍🤝‍🧑🏻👩🏾‍🤝‍👨🏿👬🏿

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Will this PR be considered for inclusion?

[arvinxx]

@kele527 会，不过要等 1.0 发布后了，最近没什么时间 review PR。

[lobehubbot]

Bot detected the issue body's language is not English, translate it automatically. 👯👭🏻🧑‍🤝‍🧑👫🧑🏿‍🤝‍🧑🏻👩🏾‍🤝‍👨🏿👬🏿

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@kele527 Yes, but we have to wait until 1.0 is released. I don’t have much time to review PRs recently.