**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:`

if (!(range_col_type->isValueRepresentedByInteger() && range_col_type->getSizeOfValueInMemory() <= sizeof(Int64)))
                throw Exception{"Illegal type " + range_col_type->getName() + " of fourth argument of function "
                        + getName() + " must be convertible to Int64.",
                    ErrorCodes::ILLEGAL_COLUMN};
        }
        if (dictionary_key_type == DictionaryKeyType::simple)
        {
            if (!key_column_type.isUInt64())
                throw Exception{"Second argument of function " + getName() + " must be " + dictionary->getStructure().getKeyDescription(),
                    ErrorCodes::TYPE_MISMATCH};
            return dictionary->hasKeys({key_column}, {std::make_shared<DataTypeUInt64>()});
        }
        else if (dictionary_key_type == DictionaryKeyType::complex)
        {
            if (!key_column_type.isTuple())
                throw Exception{"Second argument of function " + getName() + " must be " + dictionary->getStructure().getKeyDescription(),
                    ErrorCodes::TYPE_MISMATCH};
            
            ColumnPtr key_column_full = key_column->convertToFullColumnIfConst();
            const auto & key_columns = typeid_cast<const ColumnTuple &>(*key_column_full).getColumnsCopy();
            const auto & key_types = static_cast<const DataTypeTuple &>(*key_column_with_type.type).getElements();
            return dictionary->hasKeys(key_columns, key_types);
        }
        else
            return dictionary->hasKeys({key_column, range_col}, {std::make_shared<DataTypeUInt64>(), range_col_type});
    }
private:
    mutable FunctionDictHelper helper;
};
enum class DictionaryGetFunctionType