Add support for API key configuration in LiteLLM

[Devanshusp]

🚀 The feature

Allow the LiteLLM integration to use an API key specified in the configuration object instead of requiring it to be set as an environment variable.

Motivation, pitch

Right now, the LiteLLM integration only allows setting the API key through environment variables, which isn't always the most convenient option. By allowing the API key to be specified directly in the configuration object (self.config.api_key), we make it easier for developers to manage their API keys within their application’s settings.

[Jai0401]

@Dev-Khant is this issue open for contribution?

[Dev-Khant]

@Devanshusp Are you working on the active PR? Please let us know.

[Devanshusp]

Yes @Dev-Khant, working on closing out this issue with #1747

[Dev-Khant]

Yes @Dev-Khant, working on closing out this issue with #1747

Sounds good, I have left a comment there. Please have a look.

[memsranga]

Hi @Devanshusp , are you still working on this?

[dhirenmathur]

Tried to generate required changes using potpie for this change for the next contributor to pick this up easily: https://app.potpie.ai/chat/019344ed-8b64-708d-8c8b-afa3877a92e7

[tarishij17]

Sharing PR #2178
@Devanshusp Pls review