**Describe the unexpected behaviour**
ClickHouse returns exception if you would try to read polygon dictionary via SELECT query.

**How to reproduce**
ClickHouse version 21.10


```
CREATE DICTIONARY polygon_dict (
    key Array(Array(Array(Array(Float64)))),
    name String,
    value UInt64
)
PRIMARY KEY key
LAYOUT(POLYGON())
SOURCE(CLICKHOUSE(table 'polygon_dict_src'))
LIFETIME(MIN 300 MAX 360);

CREATE TABLE polygon_dict_src
(
    `key` Array(Array(Array(Array(Float64)))),
    `name` String,
    `value` UInt64
)
ENGINE = Log
	
INSERT INTO polygon_dict_src SELECT [[[[1.1,2.1],[5,3],[6,4],[1,4]]]], 'some', 10;


CREATE DICTIONARY polygon_dict (
    key Array(Array(Array(Array(Float64)))),
    name String,
    value UInt64
)
PRIMARY KEY key
LAYOUT(POLYGON())
SOURCE(CLICKHOUSE(table 'polygon_dict_src'))
LIFETIME(MIN 300 MAX 360);

SELECT dictGet(polygon_dict, 'name', (2., 3.)) AS x

┌─x────┐
│ some │
└──────┘

SELECT *
FROM polygon_dict

0 rows in set. Elapsed: 0.008 sec.

Received exception from server (version 21.10.1):
Code: 1. DB::Exception: Received from localhost:9000. DB::Exception: Reading the dictionary is not allowed. (UNSUPPORTED_METHOD)
```


**Expected behavior**
It's allowed to read POLYGON dictionaries via SELECT query.

const std::string & attribute_name,
    const DataTypePtr & result_type,
    const Columns & key_columns,
    const DataTypes &,
    const ColumnPtr & default_values_column) const
{
    const auto requested_key_points = extractPoints(key_columns);
    const auto & attribute = dict_struct.getAttribute(attribute_name, result_type);
    DefaultValueProvider default_value_provider(attribute.null_value, default_values_column);
    size_t attribute_index = dict_struct.attribute_name_to_index.find(attribute_name)->second;
    const auto & attribute_values_column = attributes[attribute_index];
    auto result = attribute_values_column->cloneEmpty();
    result->reserve(requested_key_points.size());
    if (unlikely(attribute.is_nullable))
    {
        getItemsImpl<Field>(
            requested_key_points,
            [&](size_t row) { return (*attribute_values_column)[row]; },
            [&](Field & value) { result->insert(value); },
            default_value_provider);
    }
    else
    {
        auto type_call = [&](const auto & dictionary_attribute_type)
        {