Spring-ai Add OpenAi Chat and Embedding Options

• Add OpenAiChatOptions
• Add OpenAiChatOptions that implements ChatOptions and exposes all OpenAi request options, except messages and stream.
• Add OpenAiChatOptions field (as defaultOptions) to OpenAiChatClient. Implement star-up/runtime options merging on chat request creation - Add OpenAiChatOptions options field to OpenAiChatProperties. Later is set as OpenAiChatClient#defaultOptions. Use the spring.ai.openai.chat.options.* prefix to set the options.

• Add tests for properties and options merging.

• Add OpenAiEmbeddingOptions

  • Add OpenAiEmbeddingOptions class implementing the EmbeddingOptions interface.
  • Add OpenAiEmbeddingClient#defaultOptions
  • Add request merging with default and propmt options.
  • Add OopenAiEmbeddingProperties#options field of type OpenAiEmbeddingOptions

Part of #228

Comment From: markpollack

merged in 5b4784fc5673cdc82f2c121819cffa1df460d9da