add support for trezor hardware wallets

[benbu]

Using the trezor api
https://github.com/trezor/connect
https://github.com/trezor/connect/blob/v4/examples/signtx-ethereum.html

use ethereumGetAddress and ethereumSignTx

The current wallet/purse architecture may need to be refactored and made more generic to support hardware wallets.

The bip32 path for Aura is "44'/312'/0'/0'/0"

Must use ChainId 312 in transactions for aura.