[Feature]: Handling of withdrawals with unreasonably low max_fee

[matteojug]

Feature - Handling of withdrawals with unreasonably low max_fee

1. Description

When creating a withdrawal, the user can specify a max fee they are willing to pay for it to be completed. In case the signers cannot complete the withdrawal spending less than the specified amount, the should at some point reject the withdrawal.

We currently don't have any constraint on the smart contract side on the max_fee, so it's possible for user to create withdrawal requests with unreasonable max fee (eg, setting it to zero). This may cause the signers to waste fees in rejecting it, or just ignore the request indefinitely (based on the signers implementation).

This ticket is to consider how/if we want to handle this issue.