Alerting: Add SaveAlertInstancesForRule instance store method (#94505)

Alerting: Add SaveAlertInstancesForRule method to the InstanceStore interface

pkg/services/ngalert/state/testing.go

@@ -56,7 +56,11 @@ func (f *FakeInstanceStore) DeleteAlertInstances(ctx context.Context, q ...model
 	return nil
 }
 
-func (f *FakeInstanceStore) DeleteAlertInstancesByRule(ctx context.Context, key models.AlertRuleKey) error {
+func (f *FakeInstanceStore) SaveAlertInstancesForRule(ctx context.Context, key models.AlertRuleKeyWithGroup, instances []models.AlertInstance) error {
+	return nil
+}
+
+func (f *FakeInstanceStore) DeleteAlertInstancesByRule(ctx context.Context, key models.AlertRuleKeyWithGroup) error {
 	return nil
 }