**Describe the issue**
Can't insert `String` data to column with `LowCardinality` type.

Starting from 21.1 this query fails

**How to reproduce**
```sql
CREATE TABLE default.lc_test
(   
    `id` LowCardinality(String)
)
ENGINE = MergeTree
PARTITION BY tuple()
ORDER BY id;

Ok.
0 rows in set. Elapsed: 0.003 sec.


insert into lc_test values (toString('a'));
Exception on client:
Code: 49. DB::Exception: Bad cast from type DB::ColumnString to DB::ColumnLowCardinality: data for INSERT was parsed from query

```

**Additional context**
related to issue https://github.com/DarkWanderer/ClickHouse.Client/issues/66

version 20.12 ok
{
    
    
    if (null_as_default)
    {
        expr->setAlias("_expression");
        expr = makeASTFunction("assumeNotNull", std::move(expr));
    }
    expr = makeASTFunction("CAST", std::move(expr), std::make_shared<ASTLiteral>(result_column_type.getName()));
    if (null_as_default)
    {
        auto is_null = makeASTFunction("isNull", std::make_shared<ASTIdentifier>("_expression"));
        expr = makeASTFunction("tuple", std::move(expr), std::move(is_null));
    }
}
}