Move TimelineContext struct definition to a separate header.

server/TracyTimelineController.cpp

@@ -1,6 +1,7 @@
 #include <algorithm>
 
-#include "TracyImGui.hpp"
+#include "TracyTimelineItem.hpp"
+#include "TracyTimelineContext.hpp"
 #include "TracyTimelineController.hpp"
 #include "TracyView.hpp"
 
@@ -18,6 +19,10 @@ TimelineController::TimelineController( View& view, Worker& worker )
 {
 }
 
+TimelineController::~TimelineController()
+{
+}
+
 void TimelineController::FirstFrameExpired()
 {
     m_firstFrame = false;