Add BUTTON*_IMMEDIATE option

Marlin/Configuration_adv.h

@@ -4187,6 +4187,7 @@
     #define BUTTON1_WHEN_PRINTING false     // Button allowed to trigger during printing?
     #define BUTTON1_GCODE         "G28"
     #define BUTTON1_DESC          "Homing"  // Optional string to set the LCD status
+    //#define BUTTON1_IMMEDIATE             // Skip the queue and run the G-code immediately
   #endif
 
   //#define BUTTON2_PIN -1
@@ -4195,6 +4196,7 @@
     #define BUTTON2_WHEN_PRINTING false
     #define BUTTON2_GCODE         "M140 S" STRINGIFY(PREHEAT_1_TEMP_BED) "\nM104 S" STRINGIFY(PREHEAT_1_TEMP_HOTEND)
     #define BUTTON2_DESC          "Preheat for " PREHEAT_1_LABEL
+    //#define BUTTON2_IMMEDIATE
   #endif
 
   //#define BUTTON3_PIN -1
@@ -4203,6 +4205,7 @@
     #define BUTTON3_WHEN_PRINTING false
     #define BUTTON3_GCODE         "M140 S" STRINGIFY(PREHEAT_2_TEMP_BED) "\nM104 S" STRINGIFY(PREHEAT_2_TEMP_HOTEND)
     #define BUTTON3_DESC          "Preheat for " PREHEAT_2_LABEL
+    //#define BUTTON3_IMMEDIATE
   #endif
 #endif
 

Marlin/src/MarlinCore.cpp

@@ -531,11 +531,15 @@ inline void manage_inactivity(const bool no_stepper_sleep=false) {
       constexpr millis_t CUB_DEBOUNCE_DELAY_##N = 250UL;               \
       static millis_t next_cub_ms_##N;                                 \
       if (BUTTON##N##_HIT_STATE == READ(BUTTON##N##_PIN)               \
-        && (ENABLED(BUTTON##N##_WHEN_PRINTING) || printer_not_busy)) { \
+        && (ENABLED(BUTTON##N##_WHEN_PRINTING) || printer_not_busy)    \
+      ) {                                                              \
         if (ELAPSED(ms, next_cub_ms_##N)) {                            \
           next_cub_ms_##N = ms + CUB_DEBOUNCE_DELAY_##N;               \
           CODE;                                                        \
-          queue.inject(F(BUTTON##N##_GCODE));                          \
+          if (ENABLED(BUTTON##N##_IMMEDIATE))                          \
+            gcode.process_subcommands_now(F(BUTTON##N##_GCODE));       \
+          else                                                         \
+            queue.inject(F(BUTTON##N##_GCODE));                        \
           TERN_(HAS_MARLINUI_MENU, ui.quick_feedback());               \
         }                                                              \
       }                                                                \

Marlin/src/lcd/menu/menu_item.h

@@ -23,6 +23,7 @@
 
 #include "menu.h"
 #include "../marlinui.h"
+#include "../../gcode/gcode.h" // for process_subcommands_now
 #include "../../gcode/queue.h" // for inject
 
 #include "../../inc/MarlinConfigPre.h"