Rework txpool for EIP-7702

[yperbasis]

From https://eips.ethereum.org/EIPS/eip-7702#backwards-compatibility:
"This EIP breaks the invariant that an account balance can only decrease as a result of transactions originating from that account. It also breaks the invariant that an EOA nonce may not increase after transaction execution has begun. These breakages have consequences for mempool design, and for other EIPs such as inclusion lists. However, because the accounts are listed statically in the outer transaction it is possible to modify transaction propagation rules so that conflicting transactions are not forwarded."

See also https://eips.ethereum.org/EIPS/eip-7702#transaction-propagation

[yperbasis]

See also ethereum/EIPs#8929