[ITensors] [ENHANCEMENT] contract() with specified output index ordering

[amilsted]

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

Currently, to get a contraction output with a specified index ordering, one can use something like ITensors.contract!(ITensor(k, i), randomITensor(i, j), randomITensor(j, k)).

Describe the solution you'd like

It would be nice to have an option like ITensors.contract(randomITensor(i, j), randomITensor(j, k); output_order=(k, i)).