**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_)
        : IDictionary(dict_id_)
        , dict_struct(dict_struct_)
        , source_ptr(std::move(source_ptr_))
        , dict_lifetime(dict_lifetime_)
        , input_type(input_type_)
        , point_type(point_type_)
{
    setup();
    loadData();
    calculateBytesAllocated();
}
ColumnPtr IPolygonDictionary::getColumn(