Add message_handler application

This is an example application for communication with Ethos-U kernel driver

Change-Id: I1d602682cbfdf26a2b082a56ee6c38e93a49ab8d
diff --git a/applications/CMakeLists.txt b/applications/CMakeLists.txt
index 1c8d2a7..11ed236 100644
--- a/applications/CMakeLists.txt
+++ b/applications/CMakeLists.txt
@@ -26,6 +26,8 @@
 
 add_subdirectory(threadx_demo)
 
+add_subdirectory(message_handler)
+
 if (CMAKE_CXX_COMPILER_ID STREQUAL "ARMClang")
     # Only armclang supported for now
     add_subdirectory(trustzone_inference)