feat: allow `cast wallet` to register Ledger/other HW wallets

[0xJem]

Component

Cast

Describe the feature you would like

It would be a QoL improvement to be able to add/register a Ledger wallet with a mnemonic index with cast wallet, so that it could then be used with forge script --account.

Reasoning:

• It saves the user from having to remember the mnemonic index
• cast wallet can cache the public key of the wallet
  • When feat(forge script): eliminate redundant --sender flag when using --account #10632 is implemented, it would also save the user from having to specify the --sender flag, since it's cached/can be determined

Additional context

No response