**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.

{
    if (key_columns.size() != 2)
        throw Exception(ErrorCodes::BAD_ARGUMENTS, "Expected two columns of coordinates with type Float64");
    const auto * column_x = typeid_cast<const ColumnVector<Float64>*>(key_columns[0].get());
    const auto * column_y = typeid_cast<const ColumnVector<Float64>*>(key_columns[1].get());
    if (!column_x || !column_y)
        throw Exception(ErrorCodes::TYPE_MISMATCH, "Expected columns of Float64");
    const auto rows = key_columns.front()->size();
    std::vector<Point> result;
    result.reserve(rows);
    for (size_t row = 0; row < rows; ++row)
    {
        auto x = column_x->getElement(row);
        auto y = column_y->getElement(row);
        if (isNaN(x) || isNaN(y))
            throw Exception(ErrorCodes::BAD_ARGUMENTS,
                "PolygonDictionary input point component must not be NaN");
        if (std::isinf(x) || std::isinf(y))
            throw Exception(ErrorCodes::BAD_ARGUMENTS,
                "PolygonDictionary input point component must not be infinite");
        result.emplace_back(x, y);
    }
    return result;
}
ColumnUInt8::Ptr IPolygonDictionary::hasKeys(const Columns & key_columns, const DataTypes &) const