[core] Remove old style platform configuration (#8118)

tests/component_tests/binary_sensor/test_binary_sensor.yaml

@@ -1,7 +1,8 @@
 ---
 esphome:
   name: test
-  platform: ESP8266
+
+esp8266:
   board: d1_mini_lite
 
 binary_sensor:

tests/component_tests/button/test_button.yaml

@@ -1,7 +1,8 @@
 ---
 esphome:
   name: test
-  platform: ESP8266
+
+esp8266:
   board: d1_mini_lite
 
 wifi:

tests/component_tests/deep_sleep/test_deep_sleep1.yaml

@@ -1,7 +1,8 @@
 ---
 esphome:
   name: test
-  platform: ESP32
+
+esp32:
   board: nodemcu-32s
 
 deep_sleep:

tests/component_tests/deep_sleep/test_deep_sleep2.yaml

@@ -1,7 +1,8 @@
 ---
 esphome:
   name: test
-  platform: ESP32
+
+esp32:
   board: nodemcu-32s
 
 deep_sleep:

tests/component_tests/sensor/test_sensor.yaml

@@ -1,7 +1,8 @@
 ---
 esphome:
   name: test
-  platform: ESP8266
+
+esp8266:
   board: d1_mini_lite
 
 sensor:

tests/component_tests/text_sensor/test_text_sensor.yaml

@@ -1,7 +1,8 @@
 ---
 esphome:
   name: test
-  platform: ESP8266
+
+esp8266:
   board: d1_mini_lite
 
 text_sensor:

tests/unit_tests/fixtures/yaml_util/broken_includetest.yaml

@@ -12,7 +12,7 @@ esphome:
   # not overwritten by vars in the !include above
   name: ${name}
   name_add_mac_suffix: true
-  platform: esp8266
-  board: !include {file: includes/scalar.yaml, vars: {var1: nodemcu}}
-
   libraries: !include {file: includes/list.yaml, vars: {var1: Wire}}
+
+esp8266:
+  board: !include {file: includes/scalar.yaml, vars: {var1: nodemcu}}

tests/unit_tests/fixtures/yaml_util/includetest.yaml

@@ -12,7 +12,7 @@ esphome:
   # not overwritten by vars in the !include above
   name: ${name}
   name_add_mac_suffix: true
-  platform: esp8266
-  board: !include {file: includes/scalar.yaml, vars: {var1: nodemcu}}
-
   libraries: !include {file: includes/list.yaml, vars: {var1: Wire}}
+
+esp8266:
+  board: !include {file: includes/scalar.yaml, vars: {var1: nodemcu}}

tests/unit_tests/test_yaml_util.py

@@ -10,7 +10,7 @@ def test_include_with_vars(fixture_path):
     substitutions.do_substitution_pass(actual, None)
     assert actual["esphome"]["name"] == "original"
     assert actual["esphome"]["libraries"][0] == "Wire"
-    assert actual["esphome"]["board"] == "nodemcu"
+    assert actual["esp8266"]["board"] == "nodemcu"
     assert actual["wifi"]["ssid"] == "my_custom_ssid"