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/api_server.h

@@ -69,6 +69,9 @@ class APIServer : public Component, public Controller {
 #ifdef USE_DATETIME_DATE
   void on_date_update(datetime::DateEntity *obj) override;
 #endif
+#ifdef USE_DATETIME_TIME
+  void on_time_update(datetime::TimeEntity *obj) override;
+#endif
 #ifdef USE_TEXT
   void on_text_update(text::Text *obj, const std::string &state) override;
 #endif