Pack commitments and trees as Module Types
In order to help extracting the model from the Coq files, we need a slightly better packing of Commitments and IMTs. This will also help building tests for the model in Coq (hopefully to be able to support QuickChic?)
TODO [x] Implement Commitments as Module Types [x] Lift to IMTs [x] Lift to implementations
Edited by Germán Delbianco