function to trigger nullification period, tests for the new functionality and expansion of NetworkData trait

Signed-off-by: Uncle Stretch <uncle.stretch@ghostchain.io>

pallets/networks/src/lib.rs

@@ -697,4 +697,13 @@ impl<T: Config> NetworkDataMutateHandler<NetworkData, BalanceOf<T>> for Pallet<T
     fn nullify_commission() {
         AccumulatedCommission::<T>::set(Default::default());
     }
+
+    fn trigger_nullification() {
+        if NullifyNeeded::<T>::get() {
+            Self::nullify_commission();
+            NullifyNeeded::<T>::put(false);
+        } else {
+            NullifyNeeded::<T>::put(true);
+        }
+    }
 }