**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:`

bool isDeterministic() const override { return false; }
    bool isInjective(const ColumnsWithTypeAndName & sample_columns) const override
    {
        return helper.isDictGetFunctionInjective(sample_columns);
    }
    DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
    {
        if (arguments.size() < 3)
            throw Exception{"Wrong argument count for function " + getName(), ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH};
        String dictionary_name;
        if (const auto * name_col = checkAndGetColumnConst<ColumnString>(arguments[0].column.get()))
            dictionary_name = name_col->getValue<String>();
        else
            throw Exception{"Illegal type " + arguments[0].type->getName() + " of first argument of function " + getName()
                + ", expected a const string.", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT};
        Strings attribute_names = getAttributeNamesFromColumn(arguments[1].column, arguments[1].type);
        DataTypes types;
        auto dictionary_structure = helper.getDictionaryStructure(dictionary_name);
        for (auto & attribute_name : attribute_names)
        {
            
            auto attribute = dictionary_structure.getAttribute(attribute_name);
            types.emplace_back(attribute.type);
        }
        if (types.size() > 1)
            return std::make_shared<DataTypeTuple>(types, attribute_names);
        else
            return types.front();
    }
    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const override