**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.

void setup();
    void blockToAttributes(const Block & block);
    void loadData();
    void calculateBytesAllocated();
    
    size_t getAttributeIndex(const std::string & attribute_name) const;
    
    template <typename AttributeType, typename ValueGetter, typename ValueSetter, typename DefaultValueExtractor>
    void getItemsImpl(
        const std::vector<IPolygonDictionary::Point> & requested_key_points,
        ValueGetter && get_value,
        ValueSetter && set_value,
        DefaultValueExtractor & default_value_extractor) const;
    Columns attributes;
    size_t bytes_allocated = 0;
    mutable std::atomic<size_t> query_count{0};
    mutable std::atomic<size_t> found_count{0};
    /** Since the original data may have been in the form of multi-polygons, an id is stored for each single polygon
     *  corresponding to the row in which any other attributes for this entry are located.
     */
    std::vector<size_t> polygon_index_to_attribute_value_index;
    /** Extracts a list of polygons from a column according to input_type and point_type.
     *  The polygons are appended to the dictionary with the corresponding ids.
     */
    void extractPolygons(const ColumnPtr & column);
    
    static std::vector<Point> extractPoints(const Columns &key_columns);
};
}