Combine thermal runaway and watch-period

- Make thermal protection for all hotends and/or bed into simple
switches
- Now enable `WATCH_TEMP_PERIOD` when `THERMAL_PROTECTION_HOTENDS` is
enabled
- Move detailed thermal parameters to `Configuration_adv.h`
- Add sanity checks to warn about old configurations
- Change `WATCH_TEMP_PERIOD` to seconds instead of milliseconds

Marlin/Configuration.h

@@ -284,24 +284,10 @@ Here are some standard links for getting your machine calibrated:
  * The solution: Once the temperature reaches the target, start observing.
  * If the temperature stays too far below the target (hysteresis) for too long,
  * the firmware will halt as a safety precaution.
- *
- * Note that because the countdown starts only AFTER the temperature reaches
- * the target, this will not catch a thermistor that is already disconnected
- * when the print starts!
- *
- * To enable for all extruder heaters, uncomment the two defines below:
  */
 
-// Parameters for all extruder heaters
-#define THERMAL_RUNAWAY_PROTECTION_PERIOD 40 // in seconds
-#define THERMAL_RUNAWAY_PROTECTION_HYSTERESIS 4 // in degree Celsius
-
-// To enable for the bed heater, uncomment the two defines below:
-
-// Parameters for the bed heater
-#define THERMAL_RUNAWAY_PROTECTION_BED_PERIOD 20 // in seconds
-#define THERMAL_RUNAWAY_PROTECTION_BED_HYSTERESIS 2 // in degree Celsius
-
+#define THERMAL_PROTECTION_HOTENDS // Enable thermal protection for all extruders
+#define THERMAL_PROTECTION_BED     // Enable thermal protection for the heated bed
 
 //===========================================================================
 //============================= Mechanical Settings =========================