new IntrusiveSortedList container used for uORB, WorkQueues, and WorkItems

- new intrusive linked list container (c++ template) that sorts on insertion
 - primarily for convenience inspecting things in the system like uORB or WorkQueues
 - uorb status or top sorted alphabetically 
 - work_queue status threads sorted by priority, then items sorted alphabetically within each

platforms/posix/cmake/sitl_tests.cmake

@@ -17,6 +17,7 @@ set(tests
 	hrt
 	int
 	IntrusiveQueue
+	IntrusiveSortedList
 	List
 	mathlib
 	matrix