**Describe the unexpected behaviour**
If Null being passed as dictionary key, dictGetOrDefault returns null instead of default value.

**How to reproduce**
Clickhouse version 21.5, 21.1, 20.8

```

CREATE VIEW dict_null_source AS SELECT 1 as key, 1 as val;
CREATE DICTIONARY dict_null (key UInt64, val UInt32) PRIMARY KEY key SOURCE(CLICKHOUSE(host 'localhost' user 'default' table 'dict_null_source' ))LAYOUT(FLAT)LIFETIME(300)


SELECT dictGetOrDefault('default.dict_null', 'val', CAST(NULL, 'Nullable(UInt64)'), 0) AS val

Query id: 79518a8e-b439-4d08-a0b2-85e4b3ef99eb

┌──val─┐
│ ᴺᵁᴸᴸ │
└──────┘
```

**Additional context**
```

SELECT dictGetOrDefault('default.dict_null', 'val', CAST(1, 'UInt64'))

Query id: 71ec76a1-fb61-4641-9145-79c6bfffd490


0 rows in set. Elapsed: 0.001 sec.

Received exception from server (version 21.5.1):
Code: 42. DB::Exception: Received from localhost:9000. DB::Exception: Wrong argument count for function dictGetOrDefault: While processing dictGetOrDefault('default.dict_null', 'val', CAST(1, 'UInt64')).

```

Error message in 21.1 was better:  `Number of arguments for function dictGetOrDefault doesn't match: passed 3, should be 4:`

getName(),
                     key_col_with_type.type->getName());
            if (attribute_names.size() > 1)
            {
                const auto & result_tuple_type = assert_cast<const DataTypeTuple &>(*result_type);
                Columns result_columns = dictionary->getColumns(
                    attribute_names,
                    result_tuple_type.getElements(),
                    {key_column, range_col},
                    {std::make_shared<DataTypeUInt64>(), range_col_type},
                    default_cols);
                result = ColumnTuple::create(std::move(result_columns));
            }
            else
                result = dictionary->getColumn(
                    attribute_names[0],
                    result_type,
                    {key_column, range_col},
                    {std::make_shared<DataTypeUInt64>(), range_col_type},
                    default_cols.front());
        }
        else
            throw Exception{"Unknown dictionary identifier type", ErrorCodes::BAD_ARGUMENTS};
        return result;
    }
private:
    Strings getAttributeNamesFromColumn(const ColumnPtr & column, const DataTypePtr & type) const
    {
        Strings attribute_names;
        if (const auto * name_col = checkAndGetColumnConst<ColumnString>(column.get()))