impl llmobs agent

Author: gary-huang

dd-trace-api/src/main/java/datadog/trace/api/llmobs/LLMObsConstants.java

@@ -0,0 +1,5 @@
+package datadog.trace.api.llmobs;
+
+public interface LLMObsConstants {
+  String LLM_OBS_INSTRUMENTATION_NAME = "llmobs";
+}