Track proposals in child Safes

[iamacook]

Description

Note: this issue could be tracked in a multitude of repositories (here, Safe Transaction Service, Safe{Wallet}) but is only here for simplicity.

As we natively support child Safe Accounts in Safe{Wallet}, we have received report of on-chain none collision. This occurs because children do not track nonces of untrusted transactions - proposals have no signatures.

We should investigate the possibility to track the queue when proposing via a child.

Reproduction steps

1. Propose >1 transactions in child Safe Accounts
2. Execute proposals in paren Safe Accounts

Expected behavior

Proposals are visible in child Safe Account queues, preventing proposal at the same nonce.

Additional information

• Extensive documentation