Have the on-chain verify proofs functionality as optional in off-chain groups

[vplasencia]

Right now, an off-chain group will always be able to verify proofs on-chain because the data is always updated on-chain too. It would be nice to add a boolean to have this as a feature, then off-chain group admins will be able to decide whether they want this functionality in their groups or not. By default, the value can be false, which means that it will not save any on-chain data to verify proofs from this off-chain group on-chain.

More context:
https://github.com/privacy-scaling-explorations/bandada/blob/main/apps/api/src/app/groups/groups.service.ts