refactor(dbus): D-Bus interface management with cleanup support.

Introduced a `DbusInterface` base class with a `cleanup` method to
standardize resource cleanup for D-Bus interfaces. Modified
`InterfacePiControl` to inherit from it and implemented `cleanup` logic
for proper watchdog resource handling. Adjusted `BusProvider` to manage
multiple interfaces and ensure cleanup on shutdown.

src/revpi_middleware/dbus_middleware1/dbus_helper.py

@@ -11,6 +11,18 @@ REVPI_DBUS_NAME = "com.revolutionpi.middleware1"
 REVPI_DBUS_BASE_PATH = "/com/revolutionpi/middleware1"
 
 
+class DbusInterface:
+
+    def cleanup(self):
+        """
+        Represents a method responsible for performing cleanup operations. This method is executed to properly
+        release resources, close connections, or perform other necessary finalization tasks.
+
+        This method does not take any arguments or return a value.
+        """
+        pass
+
+
 def extend_interface(*args) -> str:
     """
     Extends an interface name by appending additional segments to a pre-defined base name.