Litellm open ai compatible protocol

[ngoiyaeric]

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Add LitellmModel for OpenAI-compatible API integration.

Define LitellmModel struct with a client field for OpenAI-compatible APIs.
Implement NewLitellmModel function to create a new instance of LitellmModel.
Add GenerateText method to generate text based on a given prompt using the OpenAI-compatible API.
Include a comment explaining Litellm's compatibility with the OpenAI API protocol.

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[meguminnnnnnnnn]

Hi, thanks for contribution.

• This repository is used to store component abstractions, orchestration capabilities, Agent paradigms, and other implementation-independent code. Component implementations can be submitted in the eino-ext.
• Components in eino-ext must implement interface defined in eino/component, for example,

  eino/components/model/interface.go

  Line 29 in df93610

  type ChatModel interface {

• Why do you need this pr? I noticed that this protocol is exactly the same as OpenAI's, so maybe you can directly use the OpenAI package?

[ngoiyaeric]

Do you have any code specific improvements should I be calling https://github.com/openai/openai-go from instead? Should this be implemented on eino-ext in this package eino-ext/libs/acl as a litellm folder with open ai protocol

[meguminnnnnnnnn]

It seems that this PR simply wraps the OpenAI protocol, which has already been done in https://github.com/cloudwego/eino-ext/tree/main/components/model/openai.