[FEAT] Add Free LLM Provider (Zhipuai)

I would like to add a "completely free" LLM model - Zhipuai. The development is already completed and tested successfully.

Here are the test results:

Additionally, I noticed that after adding a new provider, the UI for initial selection and API key input does not display everything properly. To address this, I adjusted the UI and split the changes into different commits:

The effect after adjustment is as follows:

• Users need to create a Zhipu account (no financial card binding required), allowing completely hassle-free free usage of the model API.
• This model is currently integrated into Langchain.