Support for declarative build function callbacks in the Spring container

[KAMO030]

• add FunctionCallbackMethodProcessor to support parsing.
• add the FunctionCalling annotation to declare
• add FunctionCallbackMethodProcessorIT as test

Dependent on #1099

define:

public  class FunctionCallConfig {
		@FunctionCalling(name = "dateTime", description = "get the current date and time")
		public String dateTime(String location) {
			return location + " dateTime:" + LocalDateTime.now();
		}
}

use:

client.prompt().user("What is the time in New York?").functions("dateTime").call().content();

[ThomasVitale]

Thanks for your PR. Declarative tool definition via annotation has been introduced in #2064. Does that handle your use case?

Example:

class MyTools {

    @Tool(description = "Get the list of books written by the given author available in the library")
    List<Book> booksByAuthor(String author) {
        return bookService.getBooksByAuthor(new Author(author));
    }

}

@GetMapping("/chat")
String chat(String authorName) {
    return chatClient.prompt()
            .user("What books written by %s are available in the library?".formatted(authorName))
            .tools(myTools)
            .call()
            .content();
}

[ilayaperumalg]

@KAMO030 Please re-open this if you still see the issue and need help. Thanks!