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/Marlin.h

@@ -362,6 +362,10 @@ int16_t code_value_temp_diff();
 
 #if FAN_COUNT > 0
   extern int16_t fanSpeeds[FAN_COUNT];
+  #if ENABLED(PROBING_FANS_OFF)
+    extern bool fans_paused;
+    extern int16_t paused_fanSpeeds[FAN_COUNT];
+  #endif
 #endif
 
 #if ENABLED(BARICUDA)