Cleanup: remove unused includes in Compositor

And move unneeded includes in frequently used headers
to source files.

Slightly reduces compile time.

source/blender/compositor/nodes/COM_OutputFileNode.cc

@@ -17,12 +17,6 @@
  */
 
 #include "COM_OutputFileNode.h"
-#include "COM_ExecutionSystem.h"
-#include "COM_OutputFileOperation.h"
-
-#include "BKE_scene.h"
-
-#include "BLI_path_util.h"
 
 namespace blender::compositor {