[Feature request] Import aezeed format to control the onchain part of the LND wallet

LND uses the aezeed seed format for it's wallet: https://github.com/lightningnetwork/lnd/tree/master/aezeed
The wallet holds two balances:
* offchain / channel balance - 2of2 multisig according to the Lightning specification - this is not dealt with in this issue
* onchain - addresses derived only from the LND wallet seed (aezeed) which can be converted to a BIP32 Root Key. Generating the matching Master Public keys for native and nested SegWit addresses allows coin control with SpecterDesktop or Electrum: https://github.com/openoms/lightning-node-management/blob/master/RestoreLNDonchainFundsInElectrum.md#import-the-onchain-part-of-the-lnd-wallet-to-electrum-wallet

Currently the conversion is best done with:
https://guggero.github.io/cryptography-toolkit/#!/aezeed or
https://github.com/guggero/chantools

Request:
* An option to import the aezeed format 24 word seed + passphrase to SpecterDIY
* display the Master Public keys for the accounts on:
`m/84'/0'/0'/0` (p2wkh)
`m/49'/0'/0'/0` (np2wkh)