Improve temperature controls (#872)

This improves the temperature control features to allow implementing
climate platform support for homeassistant.

Also adds frostprotection module, which is also used to turn
the thermostat on and off.

kasa/smart/modules/frostprotection.py

@@ -0,0 +1,58 @@
+"""Frost protection module."""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from ...feature import Feature
+from ..smartmodule import SmartModule
+
+# TODO: this may not be necessary with __future__.annotations
+if TYPE_CHECKING:
+    from ..smartdevice import SmartDevice
+
+
+class FrostProtectionModule(SmartModule):
+    """Implementation for frost protection module.
+
+    This basically turns the thermostat on and off.
+    """
+
+    REQUIRED_COMPONENT = "frost_protection"
+    # TODO: the information required for current features do not require this query
+    QUERY_GETTER_NAME = "get_frost_protection"
+
+    def __init__(self, device: SmartDevice, module: str):
+        super().__init__(device, module)
+        self._add_feature(
+            Feature(
+                device,
+                name="Frost protection enabled",
+                container=self,
+                attribute_getter="enabled",
+                attribute_setter="set_enabled",
+                type=Feature.Type.Switch,
+            )
+        )
+
+    @property
+    def enabled(self) -> bool:
+        """Return True if frost protection is on."""
+        return self._device.sys_info["frost_protection_on"]
+
+    async def set_enabled(self, enable: bool):
+        """Enable/disable frost protection."""
+        return await self.call(
+            "set_device_info",
+            {"frost_protection_on": enable},
+        )
+
+    @property
+    def minimum_temperature(self) -> int:
+        """Return frost protection minimum temperature."""
+        return self.data["min_temp"]
+
+    @property
+    def temperature_unit(self) -> str:
+        """Return frost protection temperature unit."""
+        return self.data["temp_unit"]