**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.

#pragma once
#include <atomic>
#include <variant>
#include <Core/Block.h>
#include <Columns/ColumnDecimal.h>
#include <Columns/ColumnString.h>
#include <Common/Arena.h>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/multi_polygon.hpp>
#include "DictionaryStructure.h"
#include "IDictionary.h"
#include "IDictionarySource.h"
#include "DictionaryHelpers.h"
namespace DB
{
namespace bg = boost::geometry;
/** An interface for polygon dictionaries.
  * Polygons are read and stored as multi_polygons from boost::geometry in Euclidean coordinates.
  * An implementation should inherit from this base class and preprocess the data upon construction if needed.
  * It must override the find method of this class which retrieves the polygon containing a single point.
  */
class IPolygonDictionary : public IDictionary