Refactor Address interface

[Sam-Jeston]

The Address interface currently keeps reference to accountIndex, the change boolean and keyIndex in the BIP44 scheme. This was to allow easy addition of witnesses with client side keys.

This is brittle when interfacing with remote wallets, so we should determine and implement a cleaner solution. It may be as simple as keeping reference to the AccountIndex on the key manager, and then a quick in memory scan to determine which key matches the address we are signing for.