Refresh previous_cmd_ms during run_z_probe()

Refresh previous_cmd_ms during run_z_probe() to prevent:
stepper shutdown for expired DEFAULT_STEPPER_DEACTIVE_TIME
and extrudes for expired EXTRUDER_RUNOUT_SECONDS
(https://github.com/MarlinFirmware/MarlinDev/issues/238)

Marlin/Marlin_main.cpp

@@ -1281,6 +1281,8 @@ static void setup_for_endstop_move() {
 
   static void run_z_probe() {
 
+    refresh_cmd_timeout(); // to prevent stepper_inactive_time from running out and EXTRUDER_RUNOUT_PREVENT from extruding
+
     #if ENABLED(DELTA)
 
       float start_z = current_position[Z_AXIS];