Refactor the ‘trace’ package in skywalking-api module

skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/trace/ContextCarrier.java → skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/context/ContextCarrier.java

-package com.a.eye.skywalking.trace;
+package com.a.eye.skywalking.context;
 
+import com.a.eye.skywalking.trace.TraceSegmentRef;
 import com.a.eye.skywalking.util.StringUtil;
 import java.io.Serializable;
 

skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/trace/ContextManager.java → skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/context/ContextManager.java

-package com.a.eye.skywalking.trace;
+package com.a.eye.skywalking.context;
+
+import com.a.eye.skywalking.trace.TraceSegment;
 
 /**
  * {@link TracerContext} controls the whole context of {@link TraceSegment}. Any {@link TraceSegment} relates to

skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/trace/TracerContext.java → skywalking-sniffer/skywalking-api/src/main/java/com/a/eye/skywalking/context/TracerContext.java

-package com.a.eye.skywalking.trace;
+package com.a.eye.skywalking.context;
 
+import com.a.eye.skywalking.trace.Span;
+import com.a.eye.skywalking.trace.TraceSegment;
 import com.a.eye.skywalking.util.TraceIdGenerator;
 import java.util.ArrayList;
 import java.util.List;