Translate Intersect to MyriaJoin

[bmyerz]

We just need the rule that changes algebra.Intersect to MyriaJoin. Shuffle is already properly introduced before the Intersect by the rule ShuffleBeforeSetop.

Example query

Edges = empty(a:int,b:int);
Left = select a as v from Edges;
Right = select b as v from Edges;
i = Intersect(Left,Right);
store(i, users);