[electrum] Add native support for trezor

Summary:
This is still missing a way to migrate/switch when a different derivation path is used for the wallet (e.g. Bcash => Ecash). For now old wallets (using another derivation path than 899) will keep using the Bcash mode.
New wallets are created using the 899 derivation path by default if the device supports it.

Test Plan: Tested with the emulated and https://github.com/trezor/trezor-firmware/pull/4336.

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Subscribers: bytesofman, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D17129