Improve BLTOUCH_HEATERS_OFF functionality

- rename to PROBING_HEATERS_OFF
 - move heater pausing functionality into thermalManager
   - add variables, pause(), ispaused(), other functions
 - add fan pausing functionality -> PROBING_FANS_OFF
 - add probing_pause() wrapper
 - move pausing into do_homing_move() and do_probe_move() to minimize quiet time and so other probe types can benefit
 - example configs

Marlin/temperature.h

@@ -259,6 +259,15 @@ class Temperature {
       static int current_raw_filwidth;  //Holds measured filament diameter - one extruder only
     #endif
 
+    #if ENABLED(PROBING_HEATERS_OFF)
+      static bool paused;
+      static int16_t paused_hotend_temps[HOTENDS];
+
+      #if HAS_TEMP_BED
+        static int16_t paused_bed_temp;
+      #endif
+    #endif
+
   public:
 
     /**
@@ -452,6 +461,11 @@ class Temperature {
 
     #endif // BABYSTEPPING
 
+    #if ENABLED(PROBING_HEATERS_OFF)
+      static void pause(bool p);
+      static bool ispaused();
+    #endif
+
   private:
 
     static void set_current_temp_raw();