**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.

{
    std::vector<IPolygonDictionary::Point> points = extractPoints(key_columns);
    auto result = ColumnUInt8::create(points.size());
    auto & out = result->getData();
    size_t keys_found = 0;
    for (size_t i = 0; i < points.size(); ++i)
    {
        size_t unused_find_result = 0;
        auto & point = points[i];
        out[i] = find(point, unused_find_result);
        keys_found += out[i];
    }
    query_count.fetch_add(points.size(), std::memory_order_relaxed);
    found_count.fetch_add(keys_found, std::memory_order_relaxed);
    return result;
}
template <typename AttributeType, typename ValueGetter, typename ValueSetter, typename DefaultValueExtractor>
void IPolygonDictionary::getItemsImpl(