Define entity attributes as entity class variables (#50925)

* Define entity attributes as entity class variables

* Example coronavirus integration

* Example verisure

* Cleanup/typing fixes

* Fix Coronavirus

* Revert "Fix Coronavirus"

This reverts commit 060843860f.

* Revert "Cleanup/typing fixes"

This reverts commit 659b79e75a.

* Define entity attributes as entity class variables (attr alternative)

* Example coronavirus

* Example nut

* Example verisure

* Mark private

* Cleanup after all reverting/cherrypicking/merging

* Implement all entity properties

* Update coronavirus example

* Update nut example

* Update verisure example

* Lets not talk about this one...

* Fix multiple class attribute

homeassistant/components/verisure/switch.py

@@ -37,20 +37,14 @@ class VerisureSmartplug(CoordinatorEntity, SwitchEntity):
     ) -> None:
         """Initialize the Verisure device."""
         super().__init__(coordinator)
+
+        self._attr_name = coordinator.data["smart_plugs"][serial_number]["area"]
+        self._attr_unique_id = serial_number
+
         self.serial_number = serial_number
         self._change_timestamp = 0
         self._state = False
 
-    @property
-    def name(self) -> str:
-        """Return the name of this entity."""
-        return self.coordinator.data["smart_plugs"][self.serial_number]["area"]
-
-    @property
-    def unique_id(self) -> str:
-        """Return the unique ID for this entity."""
-        return self.serial_number
-
     @property
     def device_info(self) -> DeviceInfo:
         """Return device information about this entity."""