add support for climate action (#720)

* add support for climate action:

Following hass implementation of climate, action represents the current action the climate device is perfoming, e.g. cooling or heating

fix bang_bang climate:

make sure that the thresholds are always respected.
fixes the issue where the component would just keep on heating, regardless of the temperature range

* Updates

- Use dedicated enum for action (otherwise it gets confusing because "auto" is not a valid action)
- Add field to tell HA that action is supported
- Revert semantic changes in bang_bang

* Conditional print


Co-authored-by: Otto Winter <otto@otto-winter.com>

esphome/components/bang_bang/bang_bang_climate.h

@@ -43,7 +43,7 @@ class BangBangClimate : public climate::Climate, public Component {
   void compute_state_();
 
   /// Switch the climate device to the given climate mode.
-  void switch_to_mode_(climate::ClimateMode mode);
+  void switch_to_action_(climate::ClimateAction action);
 
   /// The sensor used for getting the current temperature
   sensor::Sensor *sensor_{nullptr};
@@ -74,11 +74,6 @@ class BangBangClimate : public climate::Climate, public Component {
    * This is so that the previous trigger can be stopped before enabling a new one.
    */
   Trigger<> *prev_trigger_{nullptr};
-  /** The climate mode that is currently active - for a `.mode = AUTO` this will
-   * contain the actual mode the device
-   *
-   */
-  climate::ClimateMode internal_mode_{climate::CLIMATE_MODE_OFF};
 
   BangBangClimateTargetTempConfig normal_config_{};
   bool supports_away_{false};