[chain] Backup / Restore Functionality

[zivkovicmilos]

Description

This effort covers the implementation of a proper backup / restore functionality for the Gno node.

Currently, there is no block backup / restore functionality, but only transaction exports, and transaction replays.

This can be cumbersome, considering users want to be able to quickly restore Gno chains from their trusted backup without having to sync with other peers.

This functionality should work with direct node access (not over JSON-RPC), for example through special commands that utilize gRPC, as there is no need for users to back up remote node states.

Successful outcome of this effort:

• The Gno node implements an efficient backup / restore functionality that a node operator can use to save chain state