**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 StorageID & dict_id_,
    const DictionaryStructure & dict_struct_,
    DictionarySourcePtr source_ptr_,
    const DictionaryLifetime dict_lifetime_,
    InputType input_type_,
    PointType point_type_,
    size_t min_intersections_,
    size_t max_depth_)
    : IPolygonDictionary(dict_id_, dict_struct_, std::move(source_ptr_), dict_lifetime_, input_type_, point_type_),
      index(min_intersections_, max_depth_, polygons),
      min_intersections(min_intersections_),
      max_depth(max_depth_)
{
}
std::shared_ptr<const IExternalLoadable> PolygonDictionaryIndexCell::clone() const
{
    return std::make_shared<PolygonDictionaryIndexCell>(
            this->getDictionaryID(),
            this->dict_struct,
            this->source_ptr->clone(),
            this->dict_lifetime,
            this->input_type,
            this->point_type,
            this->min_intersections,
            this->max_depth);
}
bool PolygonDictionaryIndexCell::find(const Point & point, size_t & polygon_index) const