[Draft] ChatLanguageModel: allow setting parameters dynamically

[langchain4j]

Issue

#837

Change

Drafted flexible (Streaming)ChatLanguageModel API that allows specifying common model parameters (e.g. model name, temparature, etc) for each request.

General checklist

• There are no breaking changes
• I have added unit and integration tests for my change
• I have manually run all the unit and integration tests in the module I have added/changed, and they are all green
• I have manually run all the unit and integration tests in the core and main modules, and they are all green
• I have added/updated the documentation
• I have added an example in the examples repo (only for "big" features)

[fmatar]

Would this also support passing of apiKeys / baseUrl / organizationId?

[langchain4j]

@fmatar I will check if/how that can be supported

[fmatar]

@langchain4j one of the approaches I implemented was to use the raw rest client for that purpose.

Then I pass all my chatCompletion request along with the security keys to the request and execute.

One major blocking factor was the passing of the model objects by ai4j since they're not serializable and I ended up writing the required serialized for them.

Happy to assist in anyway since this is a major roadblock we'd like to resolve