**Describe what's wrong**

It's not possible to use digit as tuple name, so it's not possible to parse JSON files to nested tuple structure with JSONExtract.

**Does it reproduce on recent release?**

Yes

ClickHouse 21.12


**How to reproduce**
```
WITH
    '{"1":{"key":"value"}}' AS data,
    JSONExtract(data, 'Tuple("1" Tuple(key String))') AS parsed_json
SELECT parsed_json AS ssid

Query id: 5bc7b6cf-155a-421c-ac20-f3be09bd9692


0 rows in set. Elapsed: 0.003 sec.

Received exception from server (version 21.12.1):
Code: 36. DB::Exception: Received from localhost:9000. DB::Exception: Explicitly specified names of tuple elements cannot start with digit: While processing JSONExtract('{"1":{"key":"value"}}' AS data, 'Tuple("1" Tuple(key String))') AS ssid. (BAD_ARGUMENTS)
```

**Expected behavior**

It's possible to parse JSON with digit keys.


}
}
MutableColumnPtr DataTypeTuple::createColumn() const
{
    size_t size = elems.size();
    MutableColumns tuple_columns(size);
    for (size_t i = 0; i < size; ++i)
        tuple_columns[i] = elems[i]->createColumn();
    return ColumnTuple::create(std::move(tuple_columns));
}
MutableColumnPtr DataTypeTuple::createColumn(const ISerialization & serialization) const
{
    
    
    
    const auto * current_serialization = &serialization;
    while (const auto * serialization_named = typeid_cast<const SerializationNamed *>(current_serialization))
        current_serialization = serialization_named->getNested().get();
    const auto * serialization_tuple = typeid_cast<const SerializationTuple *>(current_serialization);
    if (!serialization_tuple)
        throw Exception(ErrorCodes::LOGICAL_ERROR, "Unexpected serialization to create column of type Tuple");
    const auto & element_serializations = serialization_tuple->getElementsSerializations();
    size_t size = elems.size();
    assert(element_serializations.size() == size);
    MutableColumns tuple_columns(size);
    for (size_t i = 0; i < size; ++i)
        tuple_columns[i] = elems[i]->createColumn(*element_serializations[i]->getNested());
    return ColumnTuple::create(std::move(tuple_columns));
}
Field DataTypeTuple::getDefault() const