This commit adds an initial rough implementation father ChainNotifier
interface for neutrino, our new light client implementation. This
implementation largely borrows from the existing BtcdNotifier
implementation. As a result, a follow up commit will perform two
refactoring in order to further consolidate code.
This commit adds a new implementation of the FilteredChainView
interface. This implementation speaks purely to the p2p network and is
backed by a new experimental light client implementation.