Add start/stop charge switch [part of #28] (#36)

* Add start/stop charge switch

This switch can take the place of the binary_sensor.charging entity,
where the switch can be toggled off/on in order to stop/start charging.

The command(s) must be enabled in TeslaFi for this to work, and the
way the entity appears in Home Assistant might be less desirable
for some - that is why the entity is disabled by default.

If you want to keep the binary_sensor, but also still have the
ability to stop/start charging, you can set the switch entity to
hidden, and use some other means to toggle the switch, like with
a Button or automation calling switch.* services.

* Set charging state optimistically

custom_components/teslafi/switch.py

@@ -23,6 +23,17 @@
         available=lambda u, v, h: u and _convert_to_bool(v.get("is_climate_on")),
         cmd=lambda c, v: c.execute_command("steering_wheel_heater", statement=v),
     ),
+    TeslaFiSwitchEntityDescription(
+        key="_set_charging",
+        name="Charging",
+        icon="mdi:ev-station",
+        entity_registry_enabled_default=False,
+        device_class=SwitchDeviceClass.SWITCH,
+        entity_category=EntityCategory.DIAGNOSTIC,
+        available=lambda u, v, h: u and v.is_plugged_in,
+        value=lambda d, h: d.is_charging,
+        cmd=lambda c, v: c.execute_command("charge_start" if v else "charge_stop"),
+    ),
 ]
 
 
@@ -38,10 +49,12 @@ def _handle_coordinator_update(self) -> None:
 
     async def async_turn_on(self, **kwargs: Any) -> None:
         await self.entity_description.cmd(self.coordinator, True)
+        self._attr_is_on = True
         return self.async_write_ha_state()
 
     async def async_turn_off(self, **kwargs: Any) -> None:
         await self.entity_description.cmd(self.coordinator, False)
+        self._attr_is_on = False
         return self.async_write_ha_state()