Add entrypoints to IReificationFactory constraints

[dimitri-justeau]

These are missing in the current version (https://github.com/chocoteam/choco-solver/blob/master/solver/src/main/java/org/chocosolver/solver/constraints/IReificationFactory.java)

To do this it will be necessary to:
- Implement entrypoints in the choco-solver-capi repository
- Add these entrypoints to the C backend and SWIG interface of pychoco (backend.h, backend.c, backend.i)
- Implement, document and test python methods relying on these entrypoints.