Social Recovery via Contract Accounts

After supporting Gnosis SAFE, we can support a social recovery module/extension, either Gnosis' implementation or our own.

Some things to consider
* what does the UX look like for walking through a user to set this up?
* what are the contract account requirements? (beyond 1 of 1)

Start by reviewing the existing Gnosis SAFE support and defining the contract-account requirements beyond a 1-of-1 setup. Resolve the proposed setup UX and decide whether to use Gnosis' implementation or build an extension before identifying implementation files and acceptance tests.

Written by the indexing model from the issue text.