Make module names consistent and remove redundant module casting (#909)

Address the inconsistent naming of smart modules by removing all "Module" suffixes and aligning filenames with class names. Removes the casting of modules to the correct module type now that is is redundant. Update the adding of iot modules to use the ModuleName class rather than a free string.

kasa/smart/modules/childdevice.py

@@ -0,0 +1,10 @@
+"""Implementation for child devices."""
+
+from ..smartmodule import SmartModule
+
+
+class ChildDevice(SmartModule):
+    """Implementation for child devices."""
+
+    REQUIRED_COMPONENT = "child_device"
+    QUERY_GETTER_NAME = "get_child_device_list"