added generate random test set

Author: sumedhpendurkar

src/domains/pancake.py

@@ -93,3 +93,7 @@ def generate_state(size, steps):
             state.apply_action(np.random.choice(actions))
 
         return state
+
+    @staticmethod
+    def generate_random_state(size):
+        return Pancake(list(np.random.permutation(size)))

src/domains/sliding_tile_puzzle.py

@@ -206,3 +206,7 @@ def generate_state(size:int, n_steps_goal:int):
             state.apply_action(np.random.choice(actions))
 
         return state
+
+    @staticmethod
+    def generate_random_state(size:int):
+        raise NotImplementedError