support user to explicitly write cartesian product

[nevermore3]

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Is your feature request related to a problem? Please describe.

Multiple variables cannot be referenced in a go statement

In some scenarios, it is necessary to perform Cartesian product of two variables before outputting or expanding

$v1 = go from 'xxx' over like yield like._dst as id1;
$v2 = go from 'yyy' over like yield like._dst as id2;
$v3 = cross join $v1, $v2  yield $v1.id1 AS id1, $v2.id2 AS id2;
go from $v3.id1 over like yield edge as e;

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