**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
void visit(ASTPtr & ast, bool force_nullable)
    {
        if (visitIfLiteral(ast, force_nullable))
            return;
        if (auto * function = ast->as<ASTFunction>())
            visit(*function, force_nullable);
        else if (ast->as<ASTQueryParameter>())
            return;
        else if (ast->as<ASTIdentifier>())
            throw DB::Exception("Identifier in constant expression", ErrorCodes::SYNTAX_ERROR);
        else
            throw DB::Exception("Syntax error in constant expression", ErrorCodes::SYNTAX_ERROR);
    }
private:
    void visitChildren(ASTPtr & ast, const ColumnNumbers & dont_visit_children, const std::vector<char> & force_nullable)