Multiway join rules

Add rules to compile query to a plan using HyperCube shuffle and multiway join. 
* [x]  add rule to merge left deep join into nary join in logical plan
* [x]  add rule break nary join to hypercube shuffle and local multiway join
* [x]  add rule to instantiate local multiway join (currently we only have leapfrog, but there could be more, so this part is seperated from break break nary join)
* [x]  add rule to place sort before LeapFrogJoin.
* [x]  add unit test
* [x]  add query test
 

I think a default behavior is needed. `num_tuples` will be called if this operator is a descedent of `NaryJoin`. I will add a unified behavior for all the hard to define cardinality output operators. (e.g. assume the cardinalities of their outputs are equal if we have no idea. )