Re-introduce include_simulated_confounder as method

Signed-off-by: Andres Morales <andresmor@microsoft.com>

dowhy/causal_refuters/add_unobserved_common_cause.py

@@ -183,6 +183,18 @@ class AddUnobservedCommonCause(CausalRefuter):
             refute.add_refuter(self)
             return refute
 
+    def include_simulated_confounder(self, convergence_threshold=0.1, c_star_max=1000):
+        return include_simulated_confounder(
+            self._data,
+            self._treatment_name,
+            self._outcome_name,
+            self.kappa_t,
+            self.kappa_y,
+            self._variables_of_interest,
+            convergence_threshold,
+            c_star_max,
+        )
+
 
 def _infer_default_kappa_t(
     data: pd.DataFrame,
@@ -375,6 +387,7 @@ def include_simulated_confounder(
     outcome_name: str,
     kappa_t: float,
     kappa_y: float,
+    variables_of_interest: List,
     convergence_threshold: float = 0.1,
     c_star_max: int = 1000,
 ):
@@ -412,7 +425,7 @@ def include_simulated_confounder(
 
     # Obtaining the list of observed variables
     required_variables = True
-    observed_variables = choose_variables(required_variables)
+    observed_variables = choose_variables(required_variables, variables_of_interest)
 
     observed_variables_with_treatment_and_outcome = observed_variables + treatment_name + outcome_name