feat(open-ai): add support to configure custom query params via spring boot config

[maff]

Issue

Spring Boot follow up to langchain4j/langchain4j#3880

Change

Add custom query params support to the OpenAI Spring configuration.

General checklist

• There are no breaking changes
• I have added unit and/or integration tests for my change
• The tests cover both positive and negative cases
• [] I have manually run all the unit and integration tests in the module I have added/changed, and they are all green

• I have added/updated the documentation
• I have added an example in the examples repo (only for "big" features)

Checklist for adding new Spring Boot starter

• I have added my new starter in the root pom.xml
• I have added a org.springframework.boot.autoconfigure.AutoConfiguration.imports file in the langchain4j-{integration}-spring-boot-starter/src/main/resources/META-INF/spring/ directory