feat: jina embed support

[zijiren233]

Sweep Summary

Added support for Jina AI embeddings by implementing request conversion and response handling for the embeddings mode.

• Created new embeddings.go file in the Jina adaptor to handle embedding request conversion specifically for Jina AI.
• Updated the Jina adaptor to properly handle embeddings mode by implementing the ConvertRequest method.
• Modified the OpenAI embeddings function to use an explicit boolean parameter instead of metadata flags for better reusability.
• Updated the Baidu adaptor to use the refactored OpenAI embeddings function with the new parameter.

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