Support proxy for rerank model invocation

[ldwnt]

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1. Is this request related to a challenge you're experiencing? Tell me about your story.

The invocation of cohere API fails with 403. According to their customer service, it may be related to the IP of the caller. I'd appreciate a lot if you could support proxy for rerank model invocation.

2. Additional context or comments

No response

3. Can you help us with this feature?

• [ ] I am interested in contributing to this feature.