Add a get_target_power method to PowerManager algorithms

This would return the most recently calculated target power for a
given set of components.

Signed-off-by: Sahas Subramanian <[email protected]>

Author: shsms

src/frequenz/sdk/actor/_power_managing/_base_classes.py

@@ -293,6 +293,21 @@ def calculate_target_power(
                 didn't change.
         """
 
+    @abc.abstractmethod
+    def get_target_power(
+        self,
+        component_ids: frozenset[int],
+    ) -> Power | None:
+        """Get the target power for the given components.
+
+        Args:
+            component_ids: The component IDs to get the target power for.
+
+        Returns:
+            The target power for the given components, or `None` if there is no target
+                power.
+        """
+
     # The arguments for this method are tightly coupled to the `Matryoshka` algorithm.
     # It can be loosened up when more algorithms are added.
     @abc.abstractmethod

src/frequenz/sdk/actor/_power_managing/_matryoshka.py

@@ -152,6 +152,21 @@ def _validate_component_ids(
                     )
         return True
 
+    def get_target_power(
+        self,
+        component_ids: frozenset[int],
+    ) -> Power | None:
+        """Get the target power for the given components.
+
+        Args:
+            component_ids: The component IDs to get the target power for.
+
+        Returns:
+            The target power for the given components, or `None` if there is no target
+                power.
+        """
+        return self._target_power.get(component_ids)
+
     @override
     def calculate_target_power(
         self,