Add support for using a second signer (HW)

[fedealconada]

Description

This PR adds support for using a second signer on the KintoWallet.

This second signer is a Hardware Wallet that could either be "ledger" or "trezor".

I've provided a sample migration (script/migrations/65-test-wallet-change.s.sol) with how this can be used. There's no need to execute the migration (but if done, it won't do any change).

Type of change

• [ ] Bug fix
• [x] New feature
• [ ] Breaking change
• [ ] Dependency changes
• [ ] Deployment
• [x] Code refactor / cleanup
• [ ] Documentation or wording changes
• [ ] Other

Checklist:

• [ ] The diff is legible and has no extraneous changes
• [ ] Complex code has been commented, including external interfaces
• [ ] Tests have 100% code coverage
• [ ] The base branch is either main, or there's a description of how to merge

Issue Resolution