Spring-ai [Azure OpenAI] added support for response format in chat options

This pull request adds support for the response format option that enforces a specific format from Azure OpenAI chat models. Details of the pull request:

• Added new enum class AzureOpenAiResponseFormat
• Modified merge methods in AzureOpenAiChatModel to use new parameter
• Modfied AzureOpenAiChatOptions to include the responseFormat parameter
• Modified Azure ChatCompletionsOptionsTests to verify that new parameter is working as expected

Comment From: markpollack

thanks. merged in c26d5f624c4cf1fa34b778b7ca0c1e72b634a04c added docs