**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
{
    size_t cur_token = 0;
    size_t num_columns = structure->literals.columns();
    while (cur_column < num_columns)
    {
        size_t skip_tokens_until = structure->token_after_literal_idx[cur_column];
        while (cur_token < skip_tokens_until)
        {
            
            skipWhitespaceIfAny(istr);
            if (!checkString(structure->tokens[cur_token++], istr))
                return false;
        }