Move ESPTime into core esphome namespace (#4926)

* Prep-work for datetime entities

* Fix some includes and remove some restrictions on printing time on displays

* format

* format

* More formatting

* Move function contents

* Ignore clang-tidy

esphome/components/nextion/nextion.h

@@ -4,6 +4,8 @@
 #include <vector>
 
 #include "esphome/core/defines.h"
+#include "esphome/core/time.h"
+
 #include "esphome/components/uart/uart.h"
 #include "nextion_base.h"
 #include "nextion_component.h"
@@ -19,10 +21,6 @@
 #endif
 #endif
 
-#ifdef USE_TIME
-#include "esphome/components/time/real_time_clock.h"
-#endif
-
 namespace esphome {
 namespace nextion {
 
@@ -318,13 +316,11 @@ class Nextion : public NextionBase, public PollingComponent, public uart::UARTDe
    * Changes the font of the component named `textveiw`. Font IDs are set in the Nextion Editor.
    */
   void set_component_font(const char *component, uint8_t font_id) override;
-#ifdef USE_TIME
   /**
    * Send the current time to the nextion display.
    * @param time The time instance to send (get this with id(my_time).now() ).
    */
-  void set_nextion_rtc_time(time::ESPTime time);
-#endif
+  void set_nextion_rtc_time(ESPTime time);
 
   /**
    * Show the page with a given name.