Move Nextion external component to core

Solves #1803

advanced/esphome/nspanel_esphome_addon_upload_tft.yaml

@@ -14,16 +14,6 @@ substitutions:
   nextion_update_base_url: "https://raw.githubusercontent.com/Blackymas/NSPanel_HA_Blueprint/"
   ##############################################
 
-##### External components #####
-external_components:
-  - source:
-      type: git
-      url: https://github.com/edwardtfn/esphome
-      ref: nextion-v425
-    components:
-      - nextion  # Change this when that PR#6192 gets released (2024.2?)
-    refresh: 300s
-
 api:
   on_client_connected:
     - script.execute: report_settings

advanced/esphome/nspanel_esphome_core.yaml

@@ -21,6 +21,16 @@ substitutions:
   version: "4.2.5"
   ##############################
 
+##### External components #####
+external_components:
+  - source:
+      type: git
+      url: https://github.com/edwardtfn/esphome
+      ref: nextion-v425
+    components:
+      - nextion  # Change this when that PR#6192 gets released (2024.3?)
+    refresh: 300s
+
 ##### ESPHOME CONFIGURATION #####
 esphome:
   name: ${name}