Add support for time entities (#6399)

* Add time entities

* Add tests

* Add myself to datetime codeowners

* Fix publishing times with 0 values

* Log performing TimeCall

* Implement `on_time` trigger

* Rename var

* Fix initial value for time

* Add arg name for clarity

* Remove useless checks

esphome/components/api/list_entities.h

@@ -49,6 +49,9 @@ class ListEntitiesIterator : public ComponentIterator {
 #ifdef USE_DATETIME_DATE
   bool on_date(datetime::DateEntity *date) override;
 #endif
+#ifdef USE_DATETIME_TIME
+  bool on_time(datetime::TimeEntity *time) override;
+#endif
 #ifdef USE_TEXT
   bool on_text(text::Text *text) override;
 #endif