**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.
```

{
    Names res;
    auto func = [&res](const auto & name) { res.emplace_back(name); return true; };
    if (side == JoinTableSide::Left)
        forAllKeys<LeftSideTag>(clauses, func);
    else
        forAllKeys<RightSideTag>(clauses, func);
    return res;
}
void TableJoin::assertHasOneOnExpr() const
{
    if (!oneDisjunct())
    {
        std::vector<String> text;
        for (const auto & onexpr : clauses)
            text.push_back(onexpr.formatDebug());
        throw DB::Exception(ErrorCodes::LOGICAL_ERROR, "Expected to have only one join clause, got {}: [{}], query: '{}'",
                            clauses.size(), fmt::join(text, " | "), queryToString(table_join));
    }
}
}