**Usage**
Postgres, MySQL, and Oracle support the expression `LEFT JOIN ... ON 1 = 1`, but ClickHouse does not.

It may be possible to replace `LEFT JOIN ... ON 1 = 1` with `CROSS JOIN`, but I want to use the query in the same form for lots of databases.

Please support the expression `LEFT JOIN ... ON 1 = 1`.


**Detailed SQL**
```SQL
CREATE TABLE test
(
    `name` Nullable(String),
    `id` int
)
ENGINE = Log();

insert into test values ('a', 1) ('b', 2) (null, 3);

select * from test t1 left join (select * from test ) t2 on 1 = 1   
-- DB::Exception: Not equi-join ON expression: 1 = 1. No columns in one of equality side.: While processing 1 = 1.
```

{
    if (!column.column)
    {
        column.type = convertTypeToNullable(column.type);
        return;
    }
    ColumnPtr nullable_column = tryConvertColumnToNullable(column.column);
    if (nullable_column)
    {
        column.type = convertTypeToNullable(column.type);
        column.column = std::move(nullable_column);
    }
}
void convertColumnsToNullable(Block & block, size_t starting_pos)
{
    for (size_t i = starting_pos; i < block.columns(); ++i)
        convertColumnToNullable(block.getByPosition(i));
}
void convertColumnsToNullable(MutableColumns & mutable_columns, size_t starting_pos)
{
    for (size_t i = starting_pos; i < mutable_columns.size(); ++i)
    {
        ColumnPtr column = std::move(mutable_columns[i]);
        column = makeNullable(column);
        mutable_columns[i] = IColumn::mutate(std::move(column));
    }
}
void removeColumnNullability(ColumnWithTypeAndName & column)