Auto-sharing: take into account stage attachments

[adubovik]

Currently, DIAL Core takes into account only the attachments that are attached directly to individual chat messages.
However, according to the DIAL API, each message may also have multiple stages each of which could have attachments.

Those must also be taken into account in the auto-sharing logic, otherwise application won't have an access to the stage attachments:

ai-dial-core/src/main/java/com/epam/aidial/core/util/ProxyUtil.java

Lines 86 to 106 in f05fdad

	public static void collectAttachedFiles(ObjectNode tree, Consumer<String> consumer) {
	ArrayNode messages = (ArrayNode) tree.get("messages");
	if (messages == null) {
	return;
	}
	for (int i = 0; i < messages.size(); i++) {
	JsonNode message = messages.get(i);
	JsonNode customContent = message.get("custom_content");
	if (customContent == null) {
	continue;
	}
	ArrayNode attachments = (ArrayNode) customContent.get("attachments");
	if (attachments == null) {
	continue;
	}
	for (int j = 0; j < attachments.size(); j++) {
	JsonNode attachment = attachments.get(j);
	collectAttachedFile(attachment, consumer);
	}
	}
	}