Indexing storage scaffolding

[serg-temchenko]

As mentioned by @jmg-duarte in this comment:

What I suggested during the meeting was to start scaffolding the interface serving the boostd-data client.

A component that will be similar for use is the LevelDB service, though that for our case we'll be using RocksDB.

This component should be an abstract layer over the DB which we should use for storage indices to the data pieces stored in the storage provider system.

Please refer to the boostd-data component docs and our implementation guidelines.