2.5 - Leverage implementation to contextualise and finalise full architecture of Zaino

[idky137]

Finalise design and spec of the remote wallet service (RemoteReadStateService / Extended "cli-wallet" gRPC Service). Provide full spec for consumers (wallets / block explorers) of both the public methods provided in the Zaino-state lib (for local chain access), and the remote services provided by the Zaino server.

• Blocked on Zeroize secret key material at appropriate points zcash/librustzcash#53, Agree on a sketch of the overall wallet architecture zcash/wallet#7

Tasks

• Task 1: Decide on set of extended remote functionality for wallets and block explorers (Agree on final design spec of new remote functionality for "full node" wallets and block explorers #69, Refactor to extract common read operations zcash/librustzcash#72).
• Task 2: Finalise design documents and API specifications and add to Docs folder in Zaino.
• (Task 3): Produce ZIP containing new remote service protocol for Zcash.