[QUALITY] Generalize casting out nines

[arnaud-m]

Is your feature request related to a problem? Please describe.
Casting out nines is a sanity test to check for errors in arithmetical calculations.
It can be posted as a redundant constraint when modeling a cryptarithm.

Describe the solution you'd like

Implement a (sub-)model for casting out nines.

• its uses a generalized procedure for any base.
• It must handle additions.
• It should handle multiplications.
• It could handle other operations.

Describe alternatives you've considered
Leave it as it is since it is only a redundant constraint.