Fuzz / invariant tests

[jenpaff]

Description

We want to make sure we have enough tests and coverage on major functionality.

Example test cases:

Test on keys+spend permissions:

• User can add permissions with expiry to a session key (All the scope/spend-perms-related flows), ensure session key cannot transact after it expires, ensure session key cannot transact when revoked
• User can add and remove new admin and session keys (All the add/remove key flows), ensure only admin key can add new admin keys, ensure account has at least 1 admin key
• User can sign up with a new key and generate a session key in the same call & start signing transactions with session key

ERC20 flow:

• User can have their gas sponsored by paying in ERC20, ensure transaction is validated (signature)
• Gas estimation edge cases: what happens when user pays too much/too little
• paymentRecipient receives fees (covering all edge cases here)

Batch calls:

• User can batch multiple calls (e.g. mint + tansfer)

Upgrade Proxy/Impl flow:

• User can upgrade implementation to use new functionality

Gas cost comparison for each flow (compared to 4337)

Tests on:

• GuardedExectuor
• Delegation