Feature request: Display XPUB on Trezor

[onvej-sl]

Electrum already supports the Trezor hardware wallet and includes the feature to display an address on a Trezor device. It would be beneficial if users could also display an XPUB on a Trezor device. This feature would be particularly convenient for users with a multisig wallet, as they need to share their XPUB with other cosigners. Hardware wallets are used because they remain secure even if the computer is compromised. Therefore, user should trust the XPUB displayed on the hardware wallet rather than on the computer.