Add module support & query their information during update cycle (#243)

* Add module support & modularize existing query

This creates a base to expose more features on the supported devices.
At the moment, the most visible change is that each update cycle gets information from all available modules:
* Basic system info
* Cloud (new)
* Countdown (new)
* Antitheft (new)
* Schedule (new)
* Time (existing, implements the time/timezone handling)
* Emeter (existing, partially separated from smartdevice)

* Fix imports

* Fix linting

* Use device host instead of alias in module repr

* Add property to list available modules, print them in cli state report

* usage: fix the get_realtime query

* separate usage from schedule to avoid multi-inheritance

* Fix module querying

* Add is_supported property to modules

kasa/modules/module.py

@@ -0,0 +1,59 @@
+"""Base class for all module implementations."""
+import collections
+from abc import ABC, abstractmethod
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from kasa import SmartDevice
+
+
+# TODO: This is used for query construcing
+def merge(d, u):
+    """Update dict recursively."""
+    for k, v in u.items():
+        if isinstance(v, collections.abc.Mapping):
+            d[k] = merge(d.get(k, {}), v)
+        else:
+            d[k] = v
+    return d
+
+
+class Module(ABC):
+    """Base class implemention for all modules.
+
+    The base classes should implement `query` to return the query they want to be
+    executed during the regular update cycle.
+    """
+
+    def __init__(self, device: "SmartDevice", module: str):
+        self._device: "SmartDevice" = device
+        self._module = module
+
+    @abstractmethod
+    def query(self):
+        """Query to execute during the update cycle.
+
+        The inheriting modules implement this to include their wanted
+        queries to the query that gets executed when Device.update() gets called.
+        """
+
+    @property
+    def data(self):
+        """Return the module specific raw data from the last update."""
+        return self._device._last_update[self._module]
+
+    @property
+    def is_supported(self) -> bool:
+        """Return whether the module is supported by the device."""
+        return "err_code" not in self.data
+
+    def call(self, method, params=None):
+        """Call the given method with the given parameters."""
+        return self._device._query_helper(self._module, method, params)
+
+    def query_for_command(self, query, params=None):
+        """Create a request object for the given parameters."""
+        return self._device._create_request(self._module, query, params)
+
+    def __repr__(self) -> str:
+        return f"<Module {self.__class__.__name__} ({self._module}) for {self._device.host}>"