✨ MAX7219 idle profiler (#24375)

Marlin/src/MarlinCore.cpp

@@ -776,6 +776,10 @@ inline void manage_inactivity(const bool no_stepper_sleep=false) {
  *  - Handle Joystick jogging
  */
 void idle(bool no_stepper_sleep/*=false*/) {
+  #ifdef MAX7219_DEBUG_PROFILE
+    CodeProfiler idle_profiler;
+  #endif
+
   #if ENABLED(MARLIN_DEV_MODE)
     static uint16_t idle_depth = 0;
     if (++idle_depth > 5) SERIAL_ECHOLNPGM("idle() call depth: ", idle_depth);