Implement eip-4361 for signing

[carletex]

EIP 4361 was merged a few days ago.

Sign-In with Ethereum describes how Ethereum accounts authenticate with off-chain services by signing a standard message format parameterized by scope, session details, and security mechanisms (e.g., a nonce). The goals of this specification are to provide a self-custodied alternative to centralized identity providers, improve interoperability across off-chain services for Ethereum-based authentication, and provide wallet vendors a consistent machine-readable message format to achieve improved user experiences and consent management.

https://github.com/ethereum/EIPs/blob/master/EIPS/eip-4361.md

Long term, it would be nice to integrate it into SRE.