Add MoonPay

[PhilC813]

MoonPay provides BTC and ETH wallets when creating an account. While they don't provide documentation on the derivation path used for the BTC wallet, it appears to use BIP84, resulting in a zpub key.

(Confirmed by adding BTC to my personal MoonPay BTC wallet, providing the wallet's recovery phrase in the "BIP39 Mnemonic" field of iancoleman's "Mnemonic Code Converter" tool, selecting the BIP84 derivation path, adding the resulting zpub key to a financial aggregation app, and confirming that the transaction and balance are displayed correctly)

[nvk]

Make PR

[PhilC813]

Make PR

I'm not a contributor but I made the issue as a request and to provide the information necessary for whoever wants to work on it.