Add a calendar entity to Ridwell (#88108)

* Subclass a `DataUpdateCoordinator` for Ridwell

* Add a calendar entity to Ridwell

* Simpler unique ID

* Fix tests

* Docstring

homeassistant/components/ridwell/switch.py

@@ -4,7 +4,7 @@ from __future__ import annotations
 from typing import Any
 
 from aioridwell.errors import RidwellError
-from aioridwell.model import EventState
+from aioridwell.model import EventState, RidwellAccount
 
 from homeassistant.components.switch import SwitchEntity, SwitchEntityDescription
 from homeassistant.config_entries import ConfigEntry
@@ -38,7 +38,19 @@ async def async_setup_entry(
 
 
 class RidwellSwitch(RidwellEntity, SwitchEntity):
-    """Define a Ridwell button."""
+    """Define a Ridwell switch."""
+
+    def __init__(
+        self,
+        coordinator: RidwellDataUpdateCoordinator,
+        account: RidwellAccount,
+        description: SwitchEntityDescription,
+    ) -> None:
+        """Initialize."""
+        super().__init__(coordinator, account)
+
+        self._attr_unique_id = f"{account.account_id}_{description.key}"
+        self.entity_description = description
 
     @property
     def is_on(self) -> bool: