[switch] Add trigger `on_state` (#10108)

tests/components/switch/common.yaml

@@ -9,6 +9,18 @@ switch:
     name: "Template Switch"
     id: the_switch
     optimistic: true
+    on_state:
+      - if:
+          condition:
+            - lambda: return x;
+          then:
+            - logger.log: "Switch turned ON"
+          else:
+            - logger.log: "Switch turned OFF"
+    on_turn_on:
+      - logger.log: "Switch is now ON"
+    on_turn_off:
+      - logger.log: "Switch is now OFF"
 
 esphome:
   on_boot: