**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
{
    Block evaluated = structure->literals.cloneWithColumns(std::move(columns));
    columns = structure->literals.cloneEmptyColumns();
    if (!structure->literals.columns())
        evaluated.insert({ColumnConst::create(ColumnUInt8::create(1, 0), rows_count), std::make_shared<DataTypeUInt8>(), "_dummy"});
    structure->actions_on_literals->execute(evaluated);
    if (!evaluated || evaluated.rows() != rows_count)
        throw Exception("Number of rows mismatch after evaluation of batch of constant expressions: got " +
                        std::to_string(evaluated.rows()) + " rows for " + std::to_string(rows_count) + " expressions",
                        ErrorCodes::LOGICAL_ERROR);
    if (!evaluated.has(structure->result_column_name))
        throw Exception("Cannot evaluate template " + structure->result_column_name + ", block structure:\n" + evaluated.dumpStructure(),
                        ErrorCodes::LOGICAL_ERROR);
    rows_count = 0;
    ColumnPtr res = evaluated.getByName(structure->result_column_name).column->convertToFullColumnIfConst();
    if (!structure->null_as_default)
        return res;
    
    const auto & tuple = assert_cast<const ColumnTuple &>(*res);
    if (tuple.tupleSize() != 2)
        throw Exception("Invalid tuple size, it'a a bug", ErrorCodes::LOGICAL_ERROR);
    const auto & is_null = assert_cast<const ColumnUInt8 &>(tuple.getColumn(1));
    for (size_t i = 0; i < is_null.size(); ++i)
        if (is_null.getUInt(i))
            nulls.setBit(column_idx, offset + i);
    return tuple.getColumnPtr(0);
}
void ConstantExpressionTemplate::TemplateStructure::addNodesToCastResult(const IDataType & result_column_type, ASTPtr & expr, bool null_as_default)