[API] Sub devices and areas (#8544)

Co-authored-by: J. Nick Koston <nick@koston.org>
Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
Co-authored-by: J. Nick Koston <nick+github@koston.org>

tests/components/esphome/common.yaml

@@ -2,7 +2,9 @@ esphome:
   debug_scheduler: true
   platformio_options:
     board_build.flash_mode: dio
-  area: testing
+  area:
+    id: testing_area
+    name: Testing Area
   on_boot:
     logger.log: on_boot
   on_shutdown:
@@ -17,4 +19,20 @@ esphome:
     version: "1.1"
     on_update:
       logger.log: on_update
+  areas:
+    - id: another_area
+      name: Another area
+  devices:
+    - id: other_device
+      name: Another device
+      area_id: another_area
+    - id: test_device
+      name: Test device in main area
+      area_id: testing_area  # Reference the main area (not in areas)
+    - id: no_area_device
+      name: Device without area  # This device has no area_id
 
+binary_sensor:
+  - platform: template
+    name: Other device sensor
+    device_id: other_device