Make ChatClient and Advisor APIs more robust - Part 1

- Introduce “ChatClientRequest” and “ChatClientResponse” for propagating requests/responses in a ChatClient advisor chain.
- Structure a Prompt at the beginning of the chain, to ensure a consistent view across execution chain and observations. Any template is rendered at the beginning so that every advisor doesn’t have to do it again.
- Improve observations to include the complete view of the prompt messages, instead of only considering userText and systemText.
- Remove legacy “around” advisor type concept.
- Keep backward compatibility for AdvisedRequest, AdvisedResponse, and legacy Advisor APIs.

Relates to gh-2655

Signed-off-by: Thomas Vitale <ThomasVitale@users.noreply.github.com>

models/spring-ai-openai/src/test/java/org/springframework/ai/openai/chat/client/OpenAiChatClientIT.java

@@ -43,6 +43,7 @@ import org.springframework.ai.openai.api.OpenAiApi;
 import org.springframework.ai.openai.api.OpenAiApi.ChatCompletionRequest.AudioParameters;
 import org.springframework.ai.openai.api.tool.MockWeatherService;
 import org.springframework.ai.openai.testutils.AbstractIT;
+import org.springframework.ai.test.CurlyBracketEscaper;
 import org.springframework.ai.tool.function.FunctionToolCallback;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.test.context.SpringBootTest;
@@ -220,7 +221,7 @@ class OpenAiChatClientIT extends AbstractIT {
 				.user(u -> u
 						.text("Generate the filmography of 5 movies for Tom Hanks. " + System.lineSeparator()
 								+ "{format}")
-						.param("format", outputConverter.getFormat()))
+						.param("format", CurlyBracketEscaper.escapeCurlyBrackets(outputConverter.getFormat())))
 				.stream()
 				.chatResponse();