SmartContract: fix native NEP-17 manifest construction

Take into account event attributes declared onto the base class for
native contracts. Close #3194.

Signed-off-by: Anna Shaleva <[email protected]>

Author: AnnaShaleva

src/Neo/SmartContract/Native/NativeContract.cs

@@ -152,6 +152,9 @@ protected NativeContract()
             eventsDescriptors =
                 GetType().GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public, null, Array.Empty<Type>(), null)?.
                 GetCustomAttributes<ContractEventAttribute>().
+                // Take into account not only the contract constructor, but also the base type constructor for proper FungibleToken events handling.
+                Concat(GetType().BaseType?.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public, null, Array.Empty<Type>(), null)?.
+                GetCustomAttributes<ContractEventAttribute>()).
                 OrderBy(p => p.Order).ToList().AsReadOnly();
 
             // Calculate the initializations forks